In both cases you’re using the verb être with an adjective (capturé). The first one uses past tense (passé composé, he has been caught) the second one uses present tense (he is caught).

The difference in meaning is nothing more than the tense.

These are passive constructions in the passé composé and indicatif présent tenses, respectively. No adjectives are involved whatsoever. The difference between them two is one of tense. The second one would be more accurately translated as He’s being/getting caught.

In French the passive is constructed by following the corresponding conjugation of être with the past participle of the verb. Note that in such construction, the past participle must agree in gender and number with the subject.

NOTE: french is my mother language, it’s why I can respond.
But english is NOT, so apologies in advance for this aspect 🙂

Although previous answers are correct, it seems important to mention something else.

There is a difference between two kinds of verbs, natively rather appropriated for designate either an action/event (what is currently happening) or a result/situation (what is the state due to a previous action/event).

In the case of capturer, which belongs to the first kind above, il a été capturé is the most natural way to use it: it describes an event which already happened (and the result is something like il est prisonnier).

At the opposite, il est capturé may be rarely used: only in a special way to tell the story, where tense is always présent de l’indicatif, often for a dramatical effect.
Example for the “whole” story: Il est poursuivi. Il tombe, il se relève… Mais il est rattrapé: ça y est, il est capturé !