By L2 do you mean AC charging? If so, it should be obvious. The L2 would be on a small post. It'll look like your home charger mounted on a post. They are not superchargers and would typically charge much slower than a supercharger.
The L3 (DC chargers, Tesla calls superchargers) would be a pedestal substantially bigger.
They look like these:
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If instead you are talking about V2 vs V3 superchargers, the difference is V2 has two pedestals per cabinet, so they are numbered in pairs (1A and 1B for example). V3 has four per cabinet. I just visited one last week and noticed they are numbered in 4s (1A, 1B, 1C, 1D for example).
There's also urban chargers which are slower (limited to 75kW from memory). They look like these (the ones in the background).
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