Differences between Outlook 2010 and 2013

I have a W7 system using outlook 2010 and a W10 system using outlook 2013. I check and use the same email account in both. The W7 outlook does a very good job of not showing/deleting "junk mail", while W10 outlook does horrible. Both have the settings/options the same, I even copied the blocked senders, safe list and international (USA only) from outlook 2010 to outlook 2013. This is not intended on getting recommendations on how to block junk mail etc, but rather the question why are these behaving differently? Tx

Well it's hard to say definitively since Office is closed source, but the most likely answer is the algorithm used to detect junk mail is probably different between Outlook 2010 and Outlook 2013. Outlook has never really had a great junk filter to begin with.