There are several differences...

The original, "vintage" Tele neck pickup that most people think of, has a shiny, nickel/silver cover, Alnico III magnets, and is wound with 43 ga Formvar wire to a resistance of about 7k (I've seen 6.8k-7.6k).

Most Strat neck pickups as we know, have exposed (and usually staggered) magnet rods, Alnico V magnets, and are wound with 42 ga. wire to a resistance of 5.6k-6.2k on average (some are higher).

And of course as mentioned, the Tele neck pickups of the type I described are smaller in dimension. All of these things along with the size and weight of a typical Tele body, all combine to give a Tele a distictive sound, that differs from a typical Strat sound.