The Pentium is the successor to the 486 line.
Superscaling- The Pentium has multiple instruction pipes that allow it to complete more than one instruction per clock cycle.
64 Bit Data Path- This doubles the amount of information pulled from the memory on each fetch.
MMX Instructions- (Later models) Special 64 bit functions that allowed better number crunching speed.
The Earliest Pentium's had a clock speed of 66 mhz with 60 mhz also available. Later 75,90,120,133,150,166,200,233mhz gradually became available. The Pentium was replaced by the Pentium II Line.
The Pentium Pro emerged in 1996 as a server only chip. It had a 256k-512k onchip cache. Its most direct successor is the Pentium Xeon.