Time-weighted return breaks the period at every deposit and withdrawal, computes each sub-period return, and chains them. Cash flow timing has no effect, which is why it is the standard for judging a manager or a system.
Money-weighted return - the internal-rate-of-return - weights each period by the capital present, so the timing of deposits changes the answer. Worked: a strategy returns plus 20% in the first half and minus 10% in the second. Time-weighted result: 1.20 x 0.90 = plus 8%. But if you tripled your deposit right before the second half, your money-weighted return is deeply negative, because most of your capital only experienced the losing stretch.
Both numbers are correct and they answer different questions. The strategy did well; the investor did badly. Traders who add capital after good runs live permanently in that gap, which is why a system's published record can be honest and your experience of it still terrible.
Related: internal-rate-of-return, deposit-adjusted-return, sequence-risk, benchmark