Implementation-wise, with message passing the operation to be performed is sent as a parameter to a message handler. A method call, on the other hand, is simply

Implementation-wise, with message passing the operation to be performed is sent as a parameter to a message handler. A method call, on the other hand, is simply the invocation of a subroutine stored in a record field (a function pointer). The following article provides some examples in the Oberon programming language which I found clarifying: https://www.miasap.se/obnc/data-abstraction.html https://www.miasap.se/obnc/data-abstraction.html