The Carry-Lookahead Adder design was way more superior to the Ripple Carry Adder design in time saving.
Basically, instead of waiting for each adder to calculate and pass on whether their carry was a 1, 0, or -1, making the process slow, the Carry-Lookahead Adder design introduced a sort of overview moderator also made with logic gates.
Which, instead of looking at the results of the addition or subtraction of each Adder's two bits, looked at the input bits themselves to see which of them were likely to have a carry at all.
Like a quick overhead glance that tells all the Adders that would otherwise be idle and waiting for a carry, whether to calculate or wait, based on what they held.
It did this by looking at two things — the possibility of generating a carry… and the possibility of propagating a carry.
It was obvious that the only time a carry could be generated was when both inputs were On. 1 and 1.
