I can't answer your question complete as I have a 124 and a 301 but both have been under a year plus long up-grade path since I bought them. One thing is clear, both respond to upgrades significantly. Every time I do any modification to either they just sound better; plinth, tonearm, cartridge, whatever. I just started a new plinth for the 124 today (already built one for the 301).
What I do know about my two TT's is: the 301 tends to be slightly sharper, tighter and a bit edgy and the 124 slightly smoother, bigger liquid sounding. These are only very slight differences that could be easily changed with cartridge preferences. Both are very dynamic, have great low end qualities compared to any TT I every owned.
I have yet to have them playing at the same time with relatively equal set-up's to compare. I love listening to each and have enjoyed the process of making the dozens of diy tweaks, because (so far) they all work.
I am sure you could find several hundred other comparison comments besides mine as there are tons of online info (obviously, but just saying) about these tables.
Dan