Brønsted-Lowry theory states that acids are proton (H+) donors, and bases are proton acceptors. Lewis theory instead focuses on electrons, with acids being electron acceptors and bases electron donors.
No electrons move under Brønsted-Lowry, with a conjugate base and conjugate acid forming. A Lewis base or Lewis acid forms in Lewis theory.
In enzyme catalysis, either form of acid and base can be present.