old 105 groupset?
 

probably talking about late 90s?

how does this compare to modern groupsets

vs modern 105?

vs modern tiagra?

sora?

it is sill 105 and good quality stuff just more cogs, lighter and ugly as can be

No thumb buttons on olde 105.

I'd say most real differences would depend on the condition of the late 90s equipment.

This year's Tiagra IS last year's 105, at least that's what a salesman told me!

Not true

I didn't BELIEVE it. The funny thing is that he was trying to sell me the 105s instead of Tiagra when he said it. He was saying something like, "Tiagra is OK and you can go with it, and the current Tiagra is about what last year's 105 was." He continued and gave me valid reasons for upgrading to 105s instead. I took it with a grain of salt rather than something literally true but it made me think Tiagras were at least decent and I did eventually go with Tiagras.

My 15 year old 7400 Dura Ace is better than my 3 year old 7800 Dura Ace.

But my 6500 Ultegra group is WAY better than my 1056 105 group.