Fender headstocks generally come in two sizes, "small" and "big".
You will find the smaller headstock on Statocasters produced from its beginnings in 1954 up until the end of 1965. In late '65 and early '66 Fender began the production of Stratocasters with a "big" headstock. "Big" headstock Fender guitars could have been the design mistake of the decade if Jimi Hendrix hadn't played his late '60s Olympic White Strat at Woodstock. The popularity of some models are player driven and this was certainly the case with "big" headstock Strats which have been scorned by vintage collectors because of their non-traditional 3-bolt neck and headstock design. What's old is generally new again. Fender offers a Reissue of it's big headstock '69 Strat and variations of the Hendrix Strat. I'm sure they are hoping that a new generation will discover the magic of Jimi Hendrix. The "big" headstock was used on Fender instruments until 1980. The switch back to the smaller headstock design came about because of the increasing demand for vintage style instruments.
Differences in the overall finished appearance of the headstock, body, and neck between vintage and later instruments. Earlier guitars still had people using their discriminating eyes and hands to apply the finishing touches to the instruments. Earlier guitars will have a slightly more smooth appearance and finished tolerances will vary from guitar to guitar. If you get a chance to compare the headstocks of earlier with later instruments you'll notice a difference in the thickness of the wood. Earlier headstocks are thicker and as a result add to the tonal differences between newer and older guitars.