They are the same thing.

For building models you will be using thin and medium CA for 99% of all your building. You will rarely be using the thick or gel CA.

The advantage to getting the CA from the LHS, is that 2 oz costs $9 - $11 vs $2 for less than 1/2 oz at the hardware store/Wal-mart.

If you keep the unused portion sealed and in a cool, dry location it will last for quite awhile.