It is also margin trading if you buy and sell before settlement. Buying a stock, selling it a day later, and using the funds to buy something else requires a margin account.
You need margin to engage in day-trading, but you can sell a settled stock & immediately use the funds to buy something else just fine as long as you then hold onto that purchase for 2 days.
https://www.fidelity.com/learning-center/trading-investing/t...