Which MacBook Pro configurations actually have tangible performance differences?

Looking to get another one (13" size) and wondering which features and to what extents actually yield differences in performance for daily work use (some increments look too close to have any). I.e. Differences in processor speeds - is 2.3GHz noticeably faster and worth higher price than 2.5GHz? Or 3.1GHz vs 3.3GHz vs 3.5GHz?

If one can't get the max combo (fastest processor + highest memory + largest storage) then which feature should take higher priority (e.g. fastest processor vs highest memory)? Do certain feature combinations produce better performance? Etcetera.