As per my little knowledge mpirun
and mpiexec
both are launcher. Can anybody tell the exact difference between mpiexec
and mpirun
?
mpiexec
is defined in the MPI standard (well, the recent versions at least) and I refer you to those (your favourite search engine will find them for you) for details.
mpirun
is a command implemented by many MPI implementations. It has never, however, been standardised and there have always been, often subtle, differences between implementations. For details see the documentation of the implementation(s) of your choice.
And yes, they are both used to launch MPI programs, these days mpiexec
is generally preferable because it is standardised.