The "1301" models are Super Beetles. They were made from model years 1971-1979. Standard Beetles were also made during those years, except that all convertibles since 1973 were the "Super Beetle" models. For 1978 & 1979, the convertible was the only model offered. (US market, only. Mexico made standard Beetles through 2003)
The "1200", "1300", "1500", "1600" refers to engine displacement in CCs (Cubic Centimeters). Horsepower varied on engines of the same displacement, due to other factors, such as intake, exhaust manifolds, heads, stroke, carb, etc. The 1600 could be from 46-50 HP.
If it has McPherson Strut front suspension, rather than the twin tube torsion bar front suspension, it's a Super Beetle. Also, the spare tire lays flat in the "trunk" of the Super Beetle.
From 1973 and up, Super Beetles had a curved windshield, while standard Beetles kept the flat windshield.
If you know the year and VIN you can tell what the original engine was when built. As a good many Bugs have had engine swaps and re-builds, the only way to know for sure what size engine you have is to remove the heads and measure the cylinders. The engine serial number (stamped on the case below the alternator stand) will usually designate the engine size by a one or two letter code, but not all builders re-numbered the engine when they rebuilt them. It was very common to bump a 1500 up to 1600 with new pistons, cylinders, etc. The cost difference was minimum and power benefits great, so very few 1500 engines were rebuilt to 1500s.
Give us the VIN and engine number and we should be able to narrow everything down for you.