Return on investment measures how much you gained relative to what you put in. It's the common yardstick for comparing investments — but to compare fairly across different time spans, you also want the annualized return.
Total vs. annualized
Total ROI is simply the gain divided by the initial amount. Annualized return converts that into a constant yearly rate, so a 50% gain over three years (about 14.5% per year) can be compared with a 20% gain over one year.
ROI ignores risk and cash flows along the way, so treat it as one input among several rather than the whole picture.