There's not just the outside of the ship itself that differs.
The space jockey/engineer is different, the Orrery is different, the chair is different, corridors are different, the carge is different, the size is different (the derelict is vastly bigger). The entire technology in fact seems different, it looks like it is "inspired" from the Space Jockey of Alien but that it's not really the same specie as things look too sophisticated and very "human" in their design while alien clearly had unknown Alien technology.
So there are at least two ways to see this:
-The Engineer and Space jockey are not related at all but the engineer were inspired by the Space Jockey from Alien.
-The Engineer are the Space Jockey, in which case then, 30 years later, it makes sense to not just "reproduce" but to make new design which is perfectly understandable but also necessary because Giger isn't in shape to comes up with a lot of things and Ridley (like every director) must be bored to hell to just "reproduce" something without having a creative input.
And I do think it's option B. Then is the Juggernaut the Derelict? That's another answer and I don't think so.
Will we see a Juggernaut or a Derelict design crash on LV-426? I do believe it'll be the juggernaut one but it doesn't change a thing, it's just a small design change, main characteristics are there and are completely similar (U shape, three vagina entrance, Orrery, Cargo) so yeah it's different but it's intended to be the same.
Concerning the Canon, they absolutely made AVP and AVP-R Canon.
Cos Prometheus and Covenant are kind of a remake of AVP and AVP-R, so it works more or less.