I noticed always a big difference in memory usage as reported by (1) Conky and (2) free (a classic command line tool).

Directly after booting, according to "free", my N900 uses already almost all of its RAM and some 100 MB swap space. After 11 days normal usage, I get about 200-250 MB swap space used, while RAM is always nearly full.

Conky reports about 170 (+/- 20) MB RAM used, both after booting and also now after 11 days usage.
Which one is more correct? Or do both programs use different definitions of "used RAM"?

(Remark: Both programs agree about swap space usage.)

Thanks for a good explanation.