Smooth is faster consistently - but the very last tenth between a pb and a racing lap is taking everything right to the limit. And in most cases that will be agressive.
In terms of numbers it would be sth like this (FZR, AS3 example, of course
CD1, 6 laps:
For my standards a great race will be 1:40s every flying lap. With that you can win 99% of races there. It's tough to pull off (for me).
My PB is a 1:40.38 (that was with draft, but I also have the clean splits to get it).
A great race I would get a fastest lap of 40.65, a couple of laps in the 40:70s to 40.80s. All this is smooth racing and keeps tires alive to do all 6 laps.
Anything under 40:60 is taking it to the limit. Very late braking into the first and last pins, rear drifting around the pins, screeching tires all the way. I get 2 attempts at this in a race, then the tires are gone.
Once you really get to know car and track you know where you can be smooth without losing time and where being too smooth is too slow.
Again the above example: For really fast laps the last pin on AS3 needs to be taken at 110%, very late brakes, very aggressive through the pin and super early on throttle out if you want really fast times. But it will eat your tires up in no time. On the other hand the first pin can be taken smoothly and you only lose a few hundreths. The chicane can also be fast and smooth and T1 has different lines, some with are agressib¡ve and super fast, others which are still fast but easier on tires.
Knowing this you can plan you laps according to the state of your tires. And you can be fast and smooth, knowingly sacrifing a couple of tenths - or trying to regain them by being aggressive at the right time.
On a hotlap you have no such concerns - 110% every inch of the track.
Cheers
aceracer