M102a and HL-L5200DW share specifications such as Printer Functions (Print), Print Technology (Laser), USB (Yes), Product Type (Monochrome Laser Printer).
The main differences: Black Print Speed A4 (M102a: 22 ppm, HL-L5200DW: 42 ppm); Print Resolution (M102a: 600 x 600 dpi, HL-L5200DW: 1200 x 1200 dpi); Automatic Duplex Printing (M102a: —, HL-L5200DW: Yes).
M102a may suit users who need its differing values, while HL-L5200DW benefits those who need its paired strengths. Review the specs table above before deciding.