Mossberg 500 vs 500A difference?

[Hawkvenom]

I just purchased a mossberg tactical 5+1 shotgun from Big 5 (Used the 20% coupon) and my pick up slip says 500A. I was wondering if there is a difference between the 500A and 500. I seen barrels that is only for 500A Mossbergs. Any thoughts are appreciated. Thanks.

[Merc1138]

I just purchased a mossberg tactical 5+1 shotgun from Big 5 (Used the 20% coupon) and my pick up slip says 500A. I was wondering if there is a difference between the 500A and 500. I seen barrels that is only for 500A Mossbergs. Any thoughts are appreciated. Thanks.

500 is the series. 500A is 12 gauge, 500B is 16 gauge, 500C is 20 gauge, 500E is .410.