When comparing both processors it tells me one of them is faster because the processor frequency is 3.4 GHz vs. 2.1 GHz.
I am afraid Intel does not provide data information or benchmark information because this type of information depends on the system configuration and the programs you have running on the computer.
If you are thinking to buy new computer, please access the link below that may help you choose the right processor for your computer needs
Core i7 would be my pick, if you have many apps running the core i7 has 4 cores with hyper-threading(8 cores). Less likely to bogg down. Double the cache and more data paths to get things done faster. Not saying it's right for you.
But it's what I have at home. Also check out the compare link above it has supported features, the core i7 has Intel® HD Graphics 4000 vs. core i3 Intel® HD Graphics 2500. Mobile has a 35W DTP and supports Intel® Virtualization Technology for Directed I/O (VT-d)
How about if they have the same system configuration and the same programs running on the computers? Which is better, an i7 3.0GHz Dual Core Processor or an i7 2.5GHz Quad Core Processor?