Is hiding different when invisible than when behind total cover?

Question

A character rolls stealth with advantage if he is invisible, because he can't be seen. Why doesn't a character get advantage for being behind total cover? The senses you rely on to detect the character is the same. It's also said advantage to stealth when you are hiding in darkness (assuming no darkvision).

Is that not RAW? Do you roll regular either way, or with advantage either way?

Consider this situation:

• Party's rogue enters the secret passageways around a room and rolls stealth to stay hidden by those inside the room. The stealth roll is just a regular roll even though the baddies inside have no way of seeing the rogue. Now if the same rogue was invisible, he would be rolling stealth with advantage because of it.

Am I missing something? Would rogue be rolling advantage either way, or on the contrary no advantages either way?

Another situation:

• Invisibility is cast on a rogue in the middle of the combat, rogue is now unseen so he can take the hide action without cover.

Would rogue now roll stealth with advantage because he is unseen or only benefit of being invisible in this situation is enabling hide action without cover? If advantage, shouldn't a rogue behind total cover during a fight also roll with advantage since he can't be seen.

Answer 1

Being invisible is not different

You do not roll with advantage if you are invisible, you are simply allowed to roll (per the "Hiding" sidebar on PHB p. 177 or here in the basic rules):

You can’t hide from a creature that can see you, and if you make noise (such as shouting a warning or knocking over a vase), you give away your position. An invisible creature can’t be seen, so it can always try to hide

You may have confused an invisible creature's advantage on attack rolls (from being unseen) with it getting advantage on Stealth checks.

Answer 2

Invisible = heavily obscured = blind = sight blocked

From the invisible condition: "For the purpose of hiding, [an invisible] creature is heavily obscured."

From the Vision and Light rules: "A heavily obscured area ... blocks vision entirely. A creature effectively suffers from the blinded condition when trying to see something in that area."

So, for the purpose of whether one creature can hide (or, I'd argue, remain hidden) from another, invisibility is exactly like having the line of sight blocked.