Difference between します and できます？


I would like to know the difference between します/しました and できます/できました.

Is the difference between the two that the first one indicates action whereas
the second one indicates ability (or perhaps possibility) of action?

Thanks.




します is the polite version of the verb する which means "to do".

できます is the polite version of the verb できる (or sometimes 出来る) which has
multiple meanings.

  * It can be the [potential form](https://en.wikipedia.org/wiki/Japanese_verb_conjugation#Potential) of the verb する. The potential form of a verb is a conjugation that expresses that the action signified by the verb _can be done_. For the verb する this conjugations happens to be irregular which is why できる looks completely different from する. Since する simply means "to do", the potential form できる means "to be able to do" or "can do", just as you assumed.
  * Besides this meaning, できる can also take on a [variety of other meanings](http://jisho.org/search/dekiru) including "to be ready / complete" and "to be made of". For more information on this usage of できる see, for example, [this answer](https://japanese.stackexchange.com/a/9597/18296).




します is the polite version of the verb する which means "to do".

できます is the polite version of the verb できる (or sometimes 出来る) which has
multiple meanings.

  * It can be the [potential form](https://en.wikipedia.org/wiki/Japanese_verb_conjugation#Potential) of the verb する. The potential form of a verb is a conjugation that expresses that the action signified by the verb _can be done_. For the verb する this conjugations happens to be irregular which is why できる looks completely different from する. Since する simply means "to do", the potential form できる means "to be able to do" or "can do", just as you assumed.
  * Besides this meaning, できる can also take on a [variety of other meanings](http://jisho.org/search/dekiru) including "to be ready / complete" and "to be made of". For more information on this usage of できる see, for example, [this answer](https://japanese.stackexchange.com/a/9597/18296).

