I would agree with some of what Vince Green says, but surely in UK military parlance bullets are named purely for their basic function, so we have Ball, which is a “plain vanilla” projectile, of a material with no special penetrative or other properties. Other rounds are distinguished as Armour Piercing, Tracer, APT, Incendiary, etc when they have particular functional properties that distinguish them from ball rounds.
I would disagree with Vince to the extent that the term Ball traditionally includes all such rounds, from the round-nose, paper-patched, lead Snider bullet to the 5.56 NATO bullet. For example Peter Labbett in his book “.303 Inch” describes the Mk.II dum-dum as “Cartridge SA Ball .303 inch Cordite Mark II, special”, and he shows on p.26 a photo of a label from a packet of hollow-point Mk IV, which reads “Cartridges S.A. Ball .303 inch Cordite, 27/7/98, Mark IV R↑L”. This nomenclature also extends to larger calibre ammunition, so for the Hispano aircraft cannon we had “Cartridge SA Ball 20mm Hispano Gun Mark 1.z.”
And surely the term FMJ means just what it says, “Full Metal Jacket”, ie any cartridge, round nose or spitzer, that is covered to the tip by a distinct metal jacket over a different core, be this lead, steel, tracer compound, incendiary material etc. And so by definition lead bullets, soft-point, hollow point, and dum-dum bullets with slits, are not FMJ. while Tracer, AP etc can be.
And just to cater for the nit-pickers, a question: Should the 8mm Lebel bullet of solid bronze with no separate jacket be classified as FMJ? :) :)