Multiple xp bars

[JinKo82]

So I am running through mayham 8 and noticed i now have 3 xp bars. can someone explain what they are counting?

[Darth Cannabis]

One is your normal xp up to level 72.

Then we have your Guardian XP, This is basically what replaced Badass levels from 2.

Lastly, we have your card xp. On the very last tab of your tab menu, there are 3 cards you can have active. Fallen Heroes, Bunker Badasses, and (sorry blanking on 3rd). You can have any one of them active at a given time with daily and weekly challenges to do on them, and rewards to unlock (skins, heads, and weapons, thou wait on those until max level).

[TheSmilingDoom]

Just to add some clarification:
top (purple): Guardian Rank
middle (yellow): regular xp, disappears at level 72
lower (green): vault card