One additional point of interest may be that the line ending is not (solely) produced by the hardware key you hit but (also) by the terminal program you use to translate that key stroke into bytes to be sent.
In many programs you can decide which line ending you want to opt for.
e.g. PuTTY
Arduino Serial Monitor
If you have no control over the sending side you may need to cater for all scenarios, but the default order for the case of both characters being sent is CR/LF (despite Arduino Serial Monitor mention it as NL & CR but sending it as CR/LF 
- NL [new line] isn’t really standard terminology. NL would be the abstract for any of the above mentioned possible line endings - LF [line feed] is the “official name” for the character with the byte value 0x0A/10 (corrected as pointed out by @Muskie 
)).
If you “remember” how old fashioned typewriters worked, you had a lever to first push the carriage all the way back to the beginning of the line and once you hit the limit it would ratchet the paper drum one line on. That’s where this convention stems from.