Are there major differences in results if you’re eating hours are decreased?
At the end of the day, IF is CICO (if you’re just considering weight loss). As long as you’re ingesting fewer calories than you’re burning in a day, it doesn’t matter which you do. Do whichever you can stick with and gets you the results you want.
Where you might get more benefit from 18:6 or 20:4 is with autophagy, a process that comes from longer fasting (usually more than 16 hours). If your goal is to engage those mechanisms, 18:6+ would be what you want.