If we ignore the actual source sounds, a bog part of the sound of analog devices are the inherent differences between repetitions of the same note. In other words, a repeated sound on an analog device will often change somewhat over time, whereas a repeated digital sample will often have a “machine gun” effect.
Here’s a really good, rel-life example of this concept, created by first recording a repeated riff on a Boss DR-100 drum machine, then simply repeating a sample of one of the sounds:
“A short comparison between the always moving analog sound vs a sample of the same source. I used my Boss DR-110, analog drum machine that lacks any sound controls other than main volume, balance and accent level (used in mid position in this example). First you can hear the 16th snare pattern, recorded straight from the DR-110; then I took one of the recorded snare hits and pasted it several times to create the same pattern.”
The same could be done on any number of analog drum boxes, most famously on the TR-808.