"seem" "seen" "better" "seems" "important" "is there actually a difference?"
Disc brakes offer advantages over rim brakes but there are disadvantages too. Research it yourself including simply searching on here (Cyclechat).
Why would you like a "better" groupset? What improvements are you seeking? Does it matter TO YOU - what other people think?
Differences: very slightly better performance, maybe; lighter; more expensive (and btw therefore better easy resale value and thus more likely to be stolen without the owner's due care - especially in cities like London and Edinburgh); consumables (chains, cassettes) much more expensive (so running costs higher).
Aerobike. Minimal actual difference unless you plan to be averaging at least 30kph and riding one will feel no different. Look for many other
aero bangs for your buck (this link just the first I found: there will be others better) not in order: deep section wheels with correct width tyres, aero handlebars, tight (ie non-flapping) clothing and shoe covers, choice of helmet.