Rat sizes - weanlings? Also, rats vs mice?

Hi guys. My search function isn't working for some reason, so here I am...

I just got my young ball python on Thursday and I'm wanting to pick up some food for next week. The breeder told me he's on live weanlings... The petstore here only sells frozen and I'm going to try them before worrying about anything else. Just not sure of the size a weanling is...

My ball is a young male, weighing either 237g or 297g. I forget what he said. I'll have to weigh him tonight.

Also, is there a big difference between feeding mice and rats besides the fact that rats are bigger? Are rats better for them?

Tia!

http://tapatalk.imageshack.com/v2/15...2dd7f56c57.jpg

http://tapatalk.imageshack.com/v2/15...e18bce99a8.jpg

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These pics should help. Rats are considered better nutritionally because they do not have as much fat content as mice and of course because they are bigger. Instead if feeding multiple mice you can offer your snake one appropriate sized rat.

Thanks so much!!

No problem!