Q: Etrecheck vs Activity Monitor

Hi,

I've noticed (and not for the first time, BTW) that the results of Etrecheck don't match those of Activity Monitor on my Mac (the pics below). For example, Etrecheck displays CPU use percentage as followings: for WindowServer 3% while Activity Monitor shows 0.7%, further on, for Activity Monitor utility these figures are  0% and 0.9% respectively, etc (the others you may want to compare on your own).  If you look at the Memory use then you'll see these figures determined in a unknown way but tied somehow up with just Virtual Memory, however judging from Apple's notes on the subject of the latter OS X Mavericks: About Activity Monitor This is not an actual consumption of RAM resources and it size is determined by the author of the app. 

So why it's decided to go with this parameter is totally unclear for me, and how to draw conclusions with regard to AM utility is unclear too. It gives different values for all types of RAM than AM does. Make sure yourselves:

How can I be sure Etrcheck displays data correctly?