Also kind of depends on which models you buy. Take a 2010 17" MBP vs a 2011 17" MBP and compare it to today's top of the line 15" rMBP with all features maxed out.
RAM: The 2010 model only goes up to 8GB, 2011 model will take 16GB aftermarket and for all we know, it could possibly take 32GB one day if such ram modules were ever made. The 2013 rMBP takes 16GB max and cannot be upgraded.
Storage: 2010 model is SATA II, 2011 model is SATA III, 2013 rMBP is PCI-E. All of them can be upgraded to 1TB, but SATA II is just SLOW, SATA III is not too shabby still.
Graphics: 2010 models are hampered with just 512MB, 2011 models come with 1GB, 2013 model comes with 2GB but also has to drive way more pixels.
Ports: 2010 model is stuck with mDP and USB 2.0. 2011 model at least has thunderbolt.
CPU: 2010 model is dual core, 2011 model is quad core, 2013 is still quad core.
As you can see, the 2011 models were insanely overpowered and even in 2013, their performance is still competitive, especially with all of their latent features being utilized, whereas the 2010 models have less than competitive performance.