Clarification on semantics around melee attacks

Question

The game uses various ways of describing a physical melee attack:

• Melee Weapon Attack
• melee attack with/using a weapon
• attack with/using a melee weapon, or attack with/using a weapon (without the melee descriptor)
• weapon attack
• melee attack

Some of the descriptions are less restrictive than others, like a "melee attack" can include a spell attack, or a "weapon attack" can include a ranged attack. But for the scope of this question, let's consider physical and melee only (no spells, no ranged).

Question: Assuming there are no further restrictions, such as requiring a specific weapon property (like finesse or heavy), or a specific damage type, then are all of these attack descriptions identical, i.e. they are interchangeable? If an attack satisfies one of these descriptions, can it be used for any other description? If they are not identical, how are they different?

The genesis of this question began when considering the various use-cases in which an unarmed strike can be used in place of an attack. The rules say that an unarmed strike can be used as a melee weapon attack. Then I started considering whether an unarmed strike could also be used in place of a generic "weapon attack," which would only be the case if a "melee weapon attack" is identical to a "weapon attack" at melee. But instead of asking this specific question, I wanted to pose the question more generically such that I don't limit it to one specific instance, but rather create a general rule to help me answer future use-cases.

Answer 1

The Sage Advice Compendium is covering the use of nomenclature here:

What does “melee weapon attack” mean: a melee attack with a weapon or an attack with a melee weapon? It means a melee attack with a weapon. Similarly, “ranged weapon attack” means a ranged attack with a weapon. Some attacks count as a melee or ranged weapon attack even if a weapon isn’t involved, as specified in the text of those attacks. For example, an unarmed strike counts as a melee weapon attack, even though the attacker’s body isn’t considered a weapon.
Here’s a bit of wording minutia: we would write “melee-weapon attack” (with a hyphen) if we meant an attack with a melee weapon.

So these are not all equivalent:

• A melee attack is any melee attack, with a weapon or otherwise. It is defined on p. 195, PHB:

Melee Attacks

Used in hand-to-hand combat, a melee attack allows you to attack a foe within your reach. A melee attack typically uses a handheld weapon such as a sword, a warhammer, or an axe. A typical monster makes a melee attack when it strikes with its claws, horns, teeth, tentacles, or other body part. A few spells also involve making a melee attack. [...]
When you are unarmed, you can fight in melee by making an unarmed strike, as shown in the weapon table in chapter 5.

• An attack with a weapon is just that, any attack with an actual weapon. Weapons are explained starting on p. 146, PHB. The Weapons table on p. 149 shows the most common weapons used in the worlds of D&D (along with unarmed strike which explicitly is not a weapon). Weapons also include improvised weapons, or other weapons like the firearms from the DMG. They do do not include unarmed strikes, spell attacks, or special attacks like shoving or grappling.

• An melee attack with a weapon is again just that, a melee attack with a weapon. An example would be the attack you get to make with green flame blade, which requires an actual weapon.

• A weapon attack is either a melee weapon attack or a ranged weapon attack.

• A melee weapon attack in most cases also is a melee attack with a weapon. Unarmed strikes also count as melee weapon attacks, even though arms or legs are not weapons, so melee weapon attacks include attacks not made with a weapon.

It is the last two that are causing most of the confusion, by including in exceptional cases a non-weapon in an attack that has "weapon attack" in its name. Other games have tried to avoid this by having a special term, for example Pathfinder 2e refers to an attack with a weapon or an unarmed attack as a strike.

Answer 2

This might not be 100% accurate if you consider all special features and edge cases, but I find it makes it easier to understand the core principles.

The game has two kinds of attacks: spell attacks and weapon attacks. These can be either melee or ranged. Unarmed strikes are specifically said to count as weapon attacks and anything that isn't a weapon turns into an improvised weapon if you use it to attack, so basically all non-spell attacks are weapon attacks.

A ranged/melee attack with a weapon requires an actual weapon, which could be an improvised one, so it rules out unarmed strikes.

The syntax for describing attacks is something like this:

[ranged|melee] [spell|weapon] attack

All attacks are either ranged or melee and spell or weapon attacks. But features referring to attacks omit these groups when the feature applies to both. Ie. "ranged attack" includes "ranged spell attack" and "ranged weapon attack".

I did not include "with a weapon" at the end of the syntax description because it doesn't describe what kind of attack we're talking about mechanically. It simply means that whatever attack we're dealing with has to be done with a weapon.

Answer 3

Inspired by this question, I made a Venn diagram of many different kinds of attacks in D&D 5e:

There are two main axes of differentiation, Melee vs Ranged attacks, and Weapon vs Spell attacks. These are relatively clear, and each attack should fit neatly in to one category of each axis.

But the "with a weapon weapon" category is a bit messy. It's not exactly synonymous with "Weapon attack". It refers to the specific items on the weapons table in the Player's Handbook. It excludes unarmed strikes (which are not done with a weapon) and "natural weapons" like teeth and claws. The other axes can sometimes get a bit muddled, as you can sometimes make a spell attack with a weapon, or make a ranged attack with a melee weapon.

I've included examples of some of the weird corner cases on the diagram. For example, the attack made when casting Booming Blade or Green Flame Blade is a regular melee weapon attack (and an "attack made with a melee weapon" if it matters), despite being part of a spell. On the other hand, the spell Magic Stone lets you enchant a pebble that then can be used (by anyone, not just you!) to make a ranged spell attack using your spellcasting attribute modifier, even if they're also using a ranged weapon like a sling for extra range. Some cases are a bit ambiguous, as with Steel Wind Strike which describes brandishing a weapon and then making several melee spell attacks, without specifically saying you're using the weapon for the striking.

There are more ways to differentiate attacks than what I could fit on my diagram. Most notably, what attribute is used for each kind of attack. In general, the melee weapon attacks use Strength while ranged weapon attacks use Dexterity, but there are lots of exceptions. Finesse weapons can use either of those attributes, and thrown melee weapons like spears and throwing axes use Strength for their ranged attacks. Spell attacks usually use the caster's spellcasting attribute, but other attacks sometimes do too (such as Shillelagh letting you make Melee weapon attacks with your spellcasting modifier instead of Strength).