My definition of an airport is one that has customs and excise facilities, otherwise they are airfields, aerodromes or airstrips; however most American civil airfields that I have visited seem to be signposted "airport" even if there is nothing there but a dilapidated hangar, a tatty C172 with the prop missing and a herd of tumbleweed galloping down the runway. Military airfields are of course air bases or air stations.
Certainly think it is of interest to consider not only the diversity of size, ie ultralight to 747/AN124, but also the diversity of types, and fly ins such as Oshkosh and the various PFA/LAA and other events still count as far as I'm concerned.
I imagine types Gatwick these days are limited to B737/747/757/767/777/787, A220/A320/A330/A340/A350/A380, 146, the odd biz-jet, ummmm... ATR, Dash-8, ummmm... that tatty old MD80 on the south side which I think is still there... Embraers and the occasional military type.