I was wondering if I should save my exp potions to use on 2x exp or just use it anytime. Do they both end up being the same or is one better than the other?

Yup, you should definitely save your exp pots for 2x event. Burst your char until its level 180 (exp pots won't increase your exp in bursting), rb it then use exp pots on 2x events for training. :)
No, it doesnot end up being the same because if you use 2x pot in non-2x event days, you just get double exp but if you use 2x pot in 2x events then the pot + 2x event gives you 4x exp in total.(2x event+2x pot=4x exp)