"to specialise in"

Hello,
are there a different meanings in refer to the verb 'to specialise. In German you different between an active and a passive way: "spezialisiert sein" und "sich spezialisieren auf". In direct translation it would be "to be specialised" and "to specialise". Does this differentiation in english exist too? Or is "to specialise in" used with both meanings, "sich spezialisieren auf" und "spezialisiert sein in"?

Thank you very much.