I'm buying a Lenovo yoga 500. I have the option of two processors
Intel® i3-4005U processor
Intel® Pentium® Processor 3825U
I don't know much about laptops so any help would be good
I will be using the device for everyday things - web browsing, Microsoft office, watching movies
Go with Intel® Core™ i3-4005U processor
The processing performance is virtually identical. The 3825U is 18 months newer than the 4005U and technology steadily progresses.
The Core i3 4005U has considerably stronger graphics performance. It's still weak by the standards of gaming graphics chips but it's enough for indie games, MOBAs, and older games. The Pentium would really struggle if you ever want to play a game.
If you can afford the i3, get the i3.