What's the difference between Realistic Likeness and Disguise Self?

Question

I'm making a Kitsune character, and I want her to have the ability to disguise herself as other people.

To do this, I can either take a feat in Realistic Likeness ...

You can precisely mimic the physical features of any individual you have encountered. When you use your racial change shape ability, you can attempt to take the form of an individual, granting you a +10 circumstance bonus on Disguise checks made to fool others with your impersonation.

... or take a feat in Magical Tail which would let me cast Disguise Self.

You make yourself – including clothing, armor, weapons, and equipment – look different. You can seem 1 foot shorter or taller, thin, fat, or in between. You cannot change your creature type (although you can appear as another subtype). Otherwise, the extent of the apparent change is up to you. You could add or obscure a minor feature or look like an entirely different person or gender.

The spell does not provide the abilities or mannerisms of the chosen form, nor does it alter the perceived tactile (touch) or audible (sound) properties of you or your equipment. If you use this spell to create a disguise, you get a +10 bonus on the Disguise check. A creature that interacts with the glamer gets a Will save to recognize it as an illusion.

So far the differences I can spot are:

• Realistic Likeness can be cast as many times as you want, while Disguise Self can only be cast twice per day (as per Magical Tail)
• Realistic Likeness can only let me look like people I have already met, whereas Disguise Self can make me look like whoever I want.

Another useful thing is that taking Magical Tail lets me get more useful spells sooner rather than later, like Charm Person or Invisibility if I decide to go that route.

Are there any other important differences between the two?

The character is a Bard, if it helps.

Answer 1

Realistic Likeness

This is a supernatural effect, thus no saving throws are allowed, and it has no duration. The bonus remains in effect until you decide to remove it.

Does not allow you to change the appearance of your equipment.

You could try to change your creature size, with a -10 on the check.

Kitsunes naturally recieve a +10 Disguise bonus to appear human (and not kitsune-y), so unless you want to mimic someone's exact appearance, this feat is unnecessary.

And finally, you should check with your GM if this feat allows you to change into anyone or just humans, as this changes the usefulness of this feat completely, like the Editor's note says:

The text of this feat states that you can mimic an “individual” which you have encountered, but it likely should specify that Kitsune have the ability to turn into humans, so GMs are encouraged to read the feat as follows: “You can precisely mimic the physical features of any human you have encountered…”

Disguise Self

This is a magical effect that works as a spell, and the save DC is based on your Charisma modifier, plus one for being a 1st level spell (thus DC 11+cha mod). Anyone who touches you, is allowed a Will save to disbelieve the effect, removing the Disguise bonus.

As a spell-like ability, it has some advantages over the actual spell. It has no verbal, somatic, or material component, nor does it require a focus.

It's important to notice that this does not change the sound your equipment does if you decide to change their appearance, so you could make your full plate look like a dress, but it will still clank when you walk on it (which also allows a Will save).

So, unless your Charisma is really high, here and then someone will disbelieve your disguises, because the save DC won't scale with your character class levels.

It also has a duration of 10 minutes per caster level (which is your HD). So at most, it will last for a few hours.

Using Both

Yes, those two abilities can help each other, Realistic Likeness grants a circunstance bonus, while Disguise Self grants an untyped bonus. So if you happen to be using both abilities at once, you could recieve up to +20 on your disguise check as long as both are to appear exactly like a specific individual.

Again, these bonus ALSO should stack with your Change Shape's ability bonus, as it is a racial bonus, as long as the form chosen is that of a human. Which is why you should check with your GM regarding that Editor's Note.

Detect Magic

People casting Detect Magic are your bane. All three abilities are magical in nature and will ping when someone casts Detect Magic around you. Though Disguise Self is the only one they can identify with a Spellcraft check, the others will at least show up as a magical effect on your character, which will raise suspicion.