The Javelins in Anthem actually play very differently. However, due to a bug, it is possible to mix various abilities or equip armor pieces from other suits.
What happens due to the bug? Currently, some players are reporting in the Anthem subreddit that they can equip their Javelin with armor pieces that are actually meant for other suits due to a glitch. It should also be possible for a class to suddenly use the abilities of one of the other Javelins.
For example, the freelancer Feefski posted a video of his Colossus, which was able to use the abilities of an Interceptor in the final battle of the Stronghold Mine against the Tyrant. In the video, you can see the bulky Colossus teleporting to the boss like an Interceptor, attacking him with invisible knives, and then raising the shield of his own class again.
The player LemonKing attempted a mixture of Interceptor/Storm and made free play unsafe. The incredibly agile Interceptor can thus make use of the powerful elemental attacks of the Storm. Together with the melee attack of his own class, LemonKing’s Javelin becomes a one-man combo machine.
How does the bug occur? The game seems to assume that users have equipped a Javelin when they are actually using another one. The bug seems to occur when players enter the forge multiple times.
While this glitch is not a “game-breaking bug”, BioWare will likely put a stop to it quickly. Many bugs and player issues have already been addressed with the day-one patch.
Bug allows Javelin to wear other equipment: This glitch also enables other strange combinations. Players report that they can equip their Javelin with armor pieces that are actually intended for other classes.
For instance, the armor pieces of the Colossus cause an Interceptor to have a cannon protruding from its chest or a Ranger to carry a huge rocket on its back.
