Here is how I tell the difference:

Productivity = I can focus on a task until I complete it and move on to the next task.

Mania = I have a great idea! I start working on it. But wait! I have another great idea! I start working on it. I have another great idea! And, these projects are all really huge. Example is I tried to crochet a blanket for every single member of my family. Picked out the yarn for all of them. I finished 3 out of 30.

Spending money on needs/wants normally: I go and get the things we need and then I still have enough for groceries and bills.

Spending money during mania = We've got a lot of cool stuff! Now what do we eat for the next 2 weeks? Oh, and the bank account is overdrawn, too! Oh crap! Let's go pawn some things so we get by..... >.<