Enanthat:
enanthate as well as its close relative cypionate are long-acting esters. The main difference is molecular weight and size. Cypionate molecule is slightly heavier while still containing the same amount of active substance (). Therefore, let's say 100 mg of enanthate contains ~12% more actual than 100 mg of cypionate (but less than for instance propionate or suspension). From the other hand, longer molecule takes more time to take apart thus making more long acting. So, cypionate produces its effect for slightly longer time. But basically both steroids are almost the same.
Long-acting steroids require less injections (maybe 1 shot per week), so they are more convenient to use comparing to short-living ones like propionate or suspension, which contains 100% of per claimed concentration but also leaves body quickly and require injections every other day.