The extra 4 GB of memory will make a noticeable difference.
Presuming you are talking about MacBook Pro:
The 2.7 GHz, 8 Gb, Intel 6100 graphics device is from early 2015, model A1502, and is either order number MF839LL/A or order number MF840LL/A, both of which use flash storage, 128 GB or 256 GB respectively; neither of them had a traditional hard drive. There is a possibility that it might still be on AppleCare, depending on what and when the previous owner bought. Geek2 Bench is about 7858.
The 2.5 GHz, 4 Gb, non-Retina, was from June 2012, model A1278, order MD101LL/A. It probably had a 500 GB or 750 GB hard drive, but might have had 128 GB or 256 GB flash memory -- though in my experience, the people who would have gone for the flash memory probably would have pushed up for the faster model or for more initial memory. Geek2 Bench is about 6690 -- about 85% as fast.
My MacBook Pro is from the same generation of the second of those, June 2012, 4 core i7 of 2.6 GHz, 15" non-retina, 8 GB memory, hard drive, Geek2 Bench 11893 (and has two graphics cards, so I have one of the uncommon models with an NVIDIA GPU in it.) I have not had any complaints about the speed -- but I do keep running into memory limits these days.
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