I am trying to transferring all my data from a journaled firewire 500gb drive (which is almost full and needs to be reformatted) to a 1tb USB2 external drive partitioned into 3 sections 2 of which are unjournaled and I seem to be loosing file sizes in the process.

I have tried transferring the data (a range of video, photos to documents) in a couple of different ways (large folders to single files) and it the sizes seem to be slightly (inconsistently) smaller. e.g. photos from 37mb to 36mb or 1 folder from 20.16gb to 20.08.

Is it something to do with journaled vs unjournaled drives? Is it unimportant?

I just want to know if I need to start again with the transferring of my data or if their is a explanation for the random file size decreases and it is okay?