The base Testosterone can have many different esters attached to it, below are the 3 most common and Testosterone Suspension which is pure Testosterone without any ester.

In general, the longer the ester is that's attached to the base, the longer the active life is and the longer you can go between shots and still maintain elevated hormone levels. It also tends to equal less pain.

The downside to this is that a longer ester is heavier which means more of the mg you're injecting is actually the ester and not the testosterone

100mg Testosterone Cypionate = 70mg Testosterone
100mg Testosterone Enanthate = 72mg Testosterone
100mg Testosterone Propionate = 84mg Testosterone
100mg Testosterone Suspension = 100mg Testosterone

So in answer to your question, you are correct - 500mg Testosterone Enanthate has 360mg of Testosterone as opposed to 500mg Testosterone Suspension which has 500mg Testosterone - Hence why it appears to be more potent on a weight for weight basis

Hope that clears it up