Diamonds – the environment in which you draw the structure – , is a 32 bit program (regardsless if you downloaded a 32 or 64 bit version). Therefore Diamonds is always installed in the folder C:\Program Files (x86)\.
BuildsoftServer – the tool within Diamonds that calculations the structure (also called ‘the calculation core’) – , can be a 32 bit or 64 bit program depending on the operating system you have.