What's the difference between crochet, knitting, and tunisian crochet?
The distinction between the crafts are the tools used and how many stitches are held at the same time.  


Crochet is done with a single hooked needle and typically only a few stitches are held at one time before being crocheted off. 
Knitting is done with two or more needles, and rows of stitches are held open before being knitted off.  
Afghan/Tunisian crocheting used a single hooked needle, but keeps an entire row of stitches held open on the needle.