Calculating Variances for Analysis of Best Practices?

#1
Hi guys, I am both new here and an absolute amateur when it comes to statistics. I do not expect you to solve anything for me, I just need a little hint.

Following situation:

What I essentially want to do is to figure out social media best practices in terms of posting time, posting frequency, post media type, and post category for rolling stock maintenance providers in Europe. I do this by measuring the engagement rate (the sum of likes, reactions, comments, shares on a single post divided by the posting site's followers) for every post and thus every category. So far, so good. Now, the problem is that there really isn't a lot of rolling stock maintenance providers in Europe that are active on social media, so I figured that rolling stock manufacturers must have about the same customer group and hence can be analyzed, too.

So, technically I have two samples (I hope that is the correct term, forgive me if not) so I should measure variance – I guess. However, as I am interested in best practices anyway, wouldn't the variances between posting time, posting frequency, post media type, and post category for the two samples be irrelevant? For example, if the rolling stock manufacturers have a different average posting time than the service providers and as a result have a higher engagement rate on their posts, wouldn't that just mean that they do a better job in terms of posting time and that's it?

If you could give me a little hint on whether or not and why I have to calculate variances (or something else) and, if yes, with which method, that would be lovely.