hesitated to choose between:
Acer: AMD A8 7410 + 8gb RAM + 1TB HDD + cheaper
Dell: I3 5005U + 4gb RAM + 500gb HDD + little expensive
it's seems obvious but i never had an AMD cpu before, and which one is better with power ?
Intel CPUs are generally more power efficient than AMD APUs. Additionally, the Core i3-5005u is more powerful than the A8-7410 in both processing performance and integrated graphics performance.
Click the following link for some game benchmarks for some integrated graphics performance and a nVidia 920m from Notebookcheck.net. The 5th generation Core i3-5005u has an integrated Intel HD 5500 graphics core. The newer 6th generation Intel Core series CPUs has the Intel HD 520 graphics core. The current 7th generation Intel Core series CPUs has the Intel HD 620 graphics core. The A8-7410 has the Radeon R5 (Beema / Carrizo-L) graphics core is the weakest in the list.
You can purchase a laptop with a 6th gen Intel Core i3-6100u (Intel HD 520) for $289. You can also purchase a laptop with a 7th gen Intel Core i3-7100u (Intel HD 620) for $349. Both come with only 4GB of RAM, so I recommend installing a 2nd stick of 4GB RAM so that the RAM will run at full speed rather than half speed. That generally improves integrated graphics performance by 10% - 15% depending on the game. As far as I am aware, all the laptops tested to get performance results in the above link have 2 sticks of RAM for best performance.