ETRTO is the one that matters
The ETRTO number (e.g. 32-622) gives tire width and bead-seat diameter in millimetres. If the second number matches your rim, the tire fits. 622 = 700c/29er, 584 = 650b/27.5", 559 = 26".
Why inch sizes lie
"26 x 1.95" and "26 x 1-3/8" can have different bead diameters and not interchange — always check the ETRTO bead number. Use the tire size converter to see ETRTO, inch and rolling circumference together.