Software Deployment

64 bit apps will not work on 32bit hardware. Some 32bit apps will install on 64bit machines (it depends on the developer and how he programmed it). I find older applications (32bit) generally don't handle 64bit apps that well.

folder placement and registry could be different, IE program files (x86) and wow6432node and wow 64 keys in registry

I like to combine my 32bit and 64bit installs into the same package whenever possible. I normally create an install.bat, below is an example from my VMware View client package that checks to see if it's 32 or 64 and runs the install accordingly.

if exist "C:\Program Files\VMware\VMware View\Client\bin\wswc.exe" goto END
if exist "C:\Program Files(x86)\VMware\VMware View\Client\bin\wswc.exe" goto END

set ProgFiles86Root=%ProgramFiles(x86)%

IF NOT "%ProgFiles86Root%"=="" (
    MSIEXEC /i "VMware View 64bit\VMware View Client64.msi" MSIFASTINSTALL=1 /qn /norestart
) ELSE (
    MSIEXEC /i "VMware View 32bit\VMware View Client.msi" MSIFASTINSTALL=1 /qn /norestart
)


:END

http://www.techtipsgeek.com/difference-between-windows-7-32-bit-64-bit-version/3871/