Game performance mostly is determined by the video card. That's the same for both, and quite doubtful for games: https://www.notebookcheck.net/AMD-Radeon-R7-M440-Benchmarks-and-Specs.169455.0.html . See if you can find benchmarks for the specific games you want to play.
For multitasking there's only a difference if all your tasks together need more than 8 GB RAM. Only you know, because you can check memory usage on your current machine.
You'll see the effect of a faster CPU (I7 versus I5) everywhere, although it might be difficult to measure unless you have big spreadsheets with big macro's.
You didn't tell about the hard disk. For speed, an SSD is far preferable above a HDD.
I have a choice between two Dell laptops: i5-7200U+16GB+R7 445 and i7-7500U+8GB+R7 445 for the same price.
I use laptop for work (mainly word, excel and browsing), internet and multimedia - occasional gaming GTA V, ARMA 3 but not latest AAA games. Is there any difference between these two configurations in terms of multitasking and game performance?
Which one should i go for?