If they hadn't used a Bluray drive they hadn't had the problems with manufactoring of blue lasers which caused them to postpone the launch of the PS3 by almost a year. So they would have released the console at the same timeframe as the Xbox 360 so the latter one wouldn't have had the time advantage. Paired with the PS2 and PS1 backwards compatibility this would have been a huge advantage. When PS3 was released backwards compatibility wasn't that big of a deal anymore because we already were in the middle of the HD-generation. Also because of the lower price the console would have been more competitive and Sony wouldn't have to axe the backwards compatibility feature in the first place.
If they hadn't used the Cell CPU then maybe the whole architecture of the console would have been different. They wouldn't have had the absurd idea to include 2 Cell CPUs, one as the main processor and one which acts as a GPU. They wouldn't have to come to the realization that this was a bad idea and wouldn't have to include a striped down Nvidia GPU at the last moment which was even less powerfull than the Xbox 360s GPU. They most likely would have developed a much more powerful GPU which was even more powerful than the one in the Xbox.
The lower price and earlier release date would have prevented many customers from switching to Xbox 360 and PS3 could have reached 100m sold units.