Originally posted by ArchAngel
The terms refer to different things - the first term refers more to a trade duration time horizon and the second refers to one potential entry/exit criteria.
Scalping is a trading style contrasted with other styles like intraday swing trading, multiday swing trading, or position trading.
Momentum trading is an entry/exit criteria which can be used by different trading styles.
Scalping isn't momentum trading but scalpers may take trades based on momentum (but not all do because different scalpers have different entry/exit methods).
Similarly, momentum trades can be entered by intraday swing or longer term traders.