Live charts use a limited number of trades received per second to form candles, while marketwatch streams complete daily OHLC data directly from the exchange, including all trades.
Daily candles from marketwatch are more accurate than those shown on live charts because they include comprehensive trade data. However, you can only use marketwatch OHLC data for daily timeframes, not for minute or hourly charts. At the end of each trading day, the system imports OHLC data from marketwatch for daily candles. Slight differences may still occur if you compare candles at different times during the day.
For better accuracy during market opening or closing periods, consider using minute or hourly candles to account for potential price fluctuations.