I am not sure, but I read that they both have similar function but they are for mutual fund only. Firstrade calls it Periodic Investment Program. www.firstrade.com/trading/mutual-funds Charles Schwab www.schwab.com/content/how-to-automatically-invest-mutual-funds
I am not a tax or financial adviser. The following is purely my personal understanding, not professional advice 👇 Yes, you need to pay 0.5% SDRT when you buy UK stocks. No if you buy ETF, funds, or US stocks.