Almost always different notes. Even Unison passages mean that different instruments play the same note in different octaves.
Exceptions are so rare that this is the only one I can think of (though there are bound to be others). In Berg’s opera Wozzeck, right after Wozzeck kills Marie, Berg has an “Invention on a Single Note”. This has the note B played twice. The second time is in unison, with every instrument playing it in different octaves, in a long, terrifying crescendo.
The first time is usually played shorter, but I consider it even scarier. It is every instrument, one joining in after the other, playing the same note at the same pitch, B under middle C.