Can someone tell me the difference between those Mimoco USB sticks:

...and this Siemens Gigaset USB Stick 108:

No it is not only the design. Granted the Mimoco sticks are way stylisher than the classic design of the Siemens Gigaset stick, but the latter can connect you to the internet.
Here you can find out more: Siemens Gigaset USB Stick 108

...if you want to buy this product & you have a residence in Germany click here:
I want to buy the Siemens Gigaset USB Stick 108!

On the other hand the latest set of Mimobot Core Series 2 USB flash drives are designed by illustrator Dino Alberto. They come fashioned in a variety of sweet cartoon monsters. The company's previous Star Wars line already was gorgeous, but there is something fascinating about this new set, like the fact that these adorable little guys all have an ingenious back-story which can be found on the sticks. The drives come in 512MB, 1GB, 2GB or 4GB capacity, and range in price from $39.95 to $109.95.
Mimoco website

My recommendation: Buy both...;)