Assuming you have the Early 2011 Macbook Pro, the change will be as follows:
CPU - Quad Core 45w to Dual Core low voltage (big change for CPU intense work, but for 90% of what people do you won't notice the difference)
GPU - The Dell only has integrated Graphics - so any gaming will be worse than on the Macbook.
Screen - Increase in resolution from either 1440x900 or 1680x1050 to 1920x1080, and gaining the IPS panel. Going from 16x10 to 16x9 (this really annoys some people)
HDD - change from traditional drive to SSD (assuming you didn't put an SSD into your Macbook). If you already had an original Apple SSD in the Macbook, then it will just be faster.
Memory - lose the potential for 16gb, limited to 8gb.
Optical bay - lose the optical drive, lose the potential for dual drives.
Battery life - can't give you a good answer on this, without a review in Linux. In Windows, the Dell can loop video for 325 minutes, which is similar to the Macbook Pro. Under heavier load, the Dell would last longer but do less processing work during that time. Once you add Linux to the mix, I'd guess a 30% decrease in battery life.
Build quality - the Dell is good, but not great. I would give a slight advantage to the Macbook.
CPU - Quad Core 45w to Dual Core low voltage (big change for CPU intense work, but for 90% of what people do you won't notice the difference)
GPU - The Dell only has integrated Graphics - so any gaming will be worse than on the Macbook.
Screen - Increase in resolution from either 1440x900 or 1680x1050 to 1920x1080, and gaining the IPS panel. Going from 16x10 to 16x9 (this really annoys some people)
HDD - change from traditional drive to SSD (assuming you didn't put an SSD into your Macbook). If you already had an original Apple SSD in the Macbook, then it will just be faster.
Memory - lose the potential for 16gb, limited to 8gb.
Optical bay - lose the optical drive, lose the potential for dual drives.
Battery life - can't give you a good answer on this, without a review in Linux. In Windows, the Dell can loop video for 325 minutes, which is similar to the Macbook Pro. Under heavier load, the Dell would last longer but do less processing work during that time. Once you add Linux to the mix, I'd guess a 30% decrease in battery life.
Build quality - the Dell is good, but not great. I would give a slight advantage to the Macbook.