Apearance.

They are 1.69 meters tall. They are quite musculare and can be any race. All first generation Thunder Warriors are male but all generations afterwards can be male or female.

During the war against the cyborge warlords on Terra, they wore mark 1 power armor. AKA Thunder Armor. Even though it inceased the users streangth like other power armor, it doesn't cover the whole body to save materials and speed up production. The Emporer needed alot of power armor fast and wasn't planing on keeping the Thunder Warriors for long anyways.

The armor only comes in yellow like lightning. The helmet is round and has a red feathers on the top like the Custodes. Instead of 2 eye holes covered by protective glass, this helmet covers the eyes with 1 visor of red protective glass. The mouth, nose and chin are uncovered. The armor covers the torso, sholders, for arms, hands, calfs and feet. It doesn't cover the thighs or upper arms. There is a big back pack for the battery like the space marine armor.

In this universe after leaving Terra all Thunder Warriors got upgraded to mark 1.5 power armer. Its still called thunder armor. (I made 1.5 armor up.) It covers the thighs and upper arms for better protection. They're mouths are also covered so they're armor can work like space suits like Space Marine armor. To make it easier to tell the difference between them and the other factions that where power armor besides being shorter, they have silver mouth plates with mouths imprinted on them.

Mark 2 armor doesn't only cover more of the body and lets Space Marines survive in space or poison gas. It also has greater defense and mobility. Mark 1.5 armor doesn't have these improvements. Also Space Marines keep getting better and better armor. Even in 40k Thunder Warriors still where mark 1.5. So even though the Empress of Pleasure clearly likes them more the the Emperor did, she still vastly prefers the Space Marines.