The series is 105
The pedal system is SPD-SL
The model numbers inlcude:
PD-5700L or PD-5700S. The letters "S" and "L" denote color (silver or black).
PD-5600, PD-5610S are the older model numbers in the 105 series.
PD-5500 and PD-6600 which was called SPD-R which uses a different cleat system with designators SM-SH90, SM-SH91, SM-SH92. I believe they were in the older 105 and Ultegra series.

The 105 series are made of the same material regardless of letter designation with variations in color.
The "series" name is what differentiates material and weight.