Showa 43mm Usd Cartridge Differences On An 09 S3

I have been giving some thought as to why my S3 is firm and wonder if either the rebound or compression damper cartridge is on its way out. I recently stripped, cleaned and put them back together but wonder if it is possible to visually tell which is the compression or rebound cartridge. I only did one at a time but as they have different part numbers there must be a difference which I couldn't pick out. Planning on checking these again hence the question.