I will not be gaming but heavy internet and spreadsheet use.
They seem similar specs…
http://www.amazon.co.uk/Lenovo-G510-15-6-inch-Laptop-Integrated/dp/B00HR6U0KK/ref=cm_cd_ql_qh_dp_t
http://www.very.co.uk/lenovo-z50-70-intelreg-coretrade-i7-processor-8gb-ram-1tb-hard-drive-wi-fi-156-inch-laptop-with-2gb-dedicated-graphics-black/1402686695.prd?affsrc=acquisition&aff=google&cm_mmc=google-_-Generic-_-Product+Viewers+2-3+days-_-_nTluScYt_44106199145
I can get £30 off the Z50 so we are looking at £550 v £570.
I think g510 has worse screen and graphics card… But better processor and integrated graphics card (which Im told is more reliable when not gaming)
Let me know your views please
Read more: Should I get a lenovo G510 or Lenovo Z50-70?