The .177” and the rare .20” definitely had the two power levels. Roughly 3 and 4.5-5 ft-lbs respectively. The .22” didn’t, full power only. Though some people retrofitted .22” barrels to .177”/.20” guns, giving you a two power .22”.
I think some folk also fitted non-factory .25” barrels, which are either fun or stupid depending on how you feel about .25” in a pistol. Or both.
I think but aren’t 100% sure that the two power thing is no longer a feature. It’s no great loss, IMHO. If you want a 3 ft-lbs springer, there are smaller, lighter, cheaper and probably better choices.
The other change I know of is the sights. Older ones have plain black sights. Later ones have fibre-optics. That’s a marmite thing. As an old-school paper-puncher, I do not like fibre-optics. Others do. Each to his own (though, obviously, those who like fibre-optics are utterly wrong and probably sick in the head ).