M3035 and ECOSYS M2640idw share specifications such as Automatic Duplex Printing (Yes), USB (Yes), Ethernet (Yes), Maximum Paper Size (Legal).
The main differences: Printer Functions (M3035: Print; Scan; Copy, ECOSYS M2640idw: Print, copy, color scan, fax); Print Technology (M3035: Laser, ECOSYS M2640idw: Kyocera ECOSYS laser); Black Print Speed A4 (M3035: 33 ppm, ECOSYS M2640idw: 42 ppm); Print Resolution (M3035: 1200 x 1200 dpi, ECOSYS M2640idw: 600 x 600; up to Fine 1200 dpi).
M3035 may suit users who need its differing values, while ECOSYS M2640idw benefits those who need its paired strengths. Review the specs table above before deciding.