I have both in the field model. They are identical, the AL2 was imported by Garcia, but they ran into financial trouble. The A300, A301, A302, and A303 were imported by Beretta. Very solid guns, quite reliable, and easy to clean. Almost all parts are interchangeable, but the A302 and A303 have a slightly different trigger, but are interchangeable. The operating rod for the AL2 and A301 are the same and work with all models. But the A302 and A303 rod is different and won't work on the earlier guns. To add to the mix, the Browning B80 is the same gun as the A303 internally, but the Browning reciever and wood are shapped differently. All barrels interchange.
The $500 price is reasonable for a Trap version, get the one that looks and feels the best to you. Great guns, you will love it! Wally Riebesell is a vendor on this site, and is a true expert on these guns. He is a great source of information and has a good inventory of parts at reasonable prices.