having owned both, a JTS in a GT and currently a TS 2.0 in a GTV they are chalk and cheese, the TS is revvy ,sonourous ,reliable and just has a wonderful character that make for a real drivers engine, my other car is a 230 BHP hybrid turbo GT and honestly the TS in the GTV is as much fun , absolutely no question! and If I am honest with the windows down and a B road to play on even more so than the derv..
The JTS which i had was 05 plate so later , however the sound as ''meh'' so so, in fact the M44 in my previous 3 series sounded better, and the the TS is markedly nicer sounding than both...in fact I think its one of the nicest sounding 4 pots currently available to buy on the used market, end of.
the jts suffered from oil starvation issues to the top end resulting in premature camshaft wear ( mine needed anew exhaust camshft at 38k) this was due to the petrol contaminating the oil and thinning it...and a hardening issue with the shafts from the factory.
as the last real ''alfa engine'' before the GM JTS the JTS is a real disappointment being both underpowered and most of the time nowhere near the 165 ponies claimed by Alfa, and unreliable and uninspiring when compared to its predecessor the fantastic TS.
so are they basically the same..? hell no! one will be viewed with respect and affection for years to come and one will simply be considered a ''blip'' .
totally agree with Symon above, i have a phase I GTV so a CF2 155 BHP 2.0 TS and its absolutely fantastic...