I'll try to sum up all the differences that i know of
HeNibbs & Battle nibbs makes a loud sound when starting to tp, it is also much taller & brighter
All voltar skins make loud sounds, louder than standard, on healbot.
Bonaparte also makes sounds when summoning drones.
Skull chopper Chucho has longer dismount quotes, giving the enemy more time to hear the direction it's in.
Expandables clunk's explosion has a louder noise and a laugh which can be heard in surround, giving away his location.
Cluck has a louder explosion and shot sound
Steel Seraph Ix has a louder shot
Loninator and Mels have louder bull summoning whistles
Clockwork yoolip has a noise that plays while teleporting, giving away his position.
8-bit Yoolip has extra sounds that play while doing actions, especially on dinos.
Hot rod derpl makes sound whenever he moves
Witch coco has louder lightning ball casts (sound AND quote)
Bumble gnaws' weedlings make sound, have wide particles and are bigger in graphics
Bumble gnaw makes noise when he moves
Same as the above for gnariachi
Gnabot also makes a louder sound when moving
Cosmic captain ksenia has a larger animation for dissapearing in to stealth
So does Dragon Huntress Ksenia
Desperado penny's claw and gun make more noise
"Ravishing" raelynn has a louder step (and looks ugly(And still has no nose))
Bionic raelynn leaves particles wherever she moves and makes louder sounds when sniping
ESC rocco does everything louder and leaves behind a trail while in vengeance as well as playing music similar to gnariachi's weedling situation.
Wraithlord scoop's quotes are louder and last longer
Wraithlord scoop's bindings are easier to see
Roboscoop plays louder sounds when using abilities
Bravely scoop IV has larger animations for bindings and generally bright colours as well as sounds during the teleport animation and a much larger tp animation.
Giga Sentorii has a loud sound during his tp animation as well as 3 smaller tp animations.
Giga Sentorii has more obvious black holes and shots
Specimen x-58 has much louder sounds and brighter attacks/abilities as well as incomprehensible quotes
Skreelator has much louder quotes and saws
Sun wukong skree is very bright and easily seen.
Sun wukong skree's totem makes noise
Yogscat skolldir has an easier to see gnome
Both forms of jotunn skoldir are bright and easy to see as well as having brighter abilities
Party Boy Mcpain has brighter everything
Titanium ted has a bigger initial marker for airstrike (the GoW symbol)
Both vinnie and spike skins have louder sounds for smoke cloud
CV&TS have music that plays during the cloud
Grim genji has a much louder step and flutter
Augmented Ayla has a louder chainwhack and makes more sound during rage
Augmented ayla and Teddy bear ayla leave behind particles when moving (AA during rage)
Abyssal swiggins is louder and has incomprehensible quotes
Loninator and Pvt. Mels have quieter sounding bulls
Skull Chopper chucho has quieter guns
Expandables clunk's shots make less noise
Creeper clunk has a quieter explosion sound and almost no sound from shots
Steel seraph Ix has a quieter refract and bond sound as well as quote
Sir jimmy has a quieter melee and quotes.
Clockwork yoolip has quieter dinos
All of leon's skins have quieter slash sounds
Hot rod derpl hsa quieter traps
Witch coco has a quieter blaze
Cheerleader penny's claw makes little noise
Both of ksenia's skins make less noise when walking
Shinobi rocco does everything quieter and has a smaller vengeance graphic.
Shinobi rocco is much darker and harder to notice
Wraithlord scoop does not make noise when moving and his hammer is dimmer(hard to see)
Wraithlord scoop is overall much darker and harder to notice
All of scoop's skins have a quieter sword slash
Giga Sentorii has a less bright beacon
Skreelator is much darker and harder to see
Demon skolldir is much darker and harder to see as well as a harder to spot gnome.
Party Boy Mcpain has quieter gun switching sounds
Party Boy Mcpain has a bigger *redacted*
Titanium ted has quieter quotes and shots
Captain vinnie is much darker and harder to see
Grim genji's shot is much harder to see
Abyssal swiggins is harder to see
If i missd any just let me know