I have the little green ones and they are marvelous. I use them to cut out applique pieces. However I think the two are quite interchangeable and if you have the larger size I don't see much need for the smaller size as both seem to come to a pretty sharp point at the tip.
For those not familiar they have a micro serrated edge so the fabric doesn't get pushed when you cut. There are several brands on the market and if the Karen Buckley ones I have are any representation they are awesome.
Welcome to the board!