Yes, there is a significant difference in speeds between the two.
The 850 Evo beats it out by a mile!
It is essentially the best Sata SSD you can buy, as it more or less tops out the available bandwidth at great value and high speeds.
M.2 is where higher performance SSDs are focused nowadays since the release of the 850 Evo.
If you don't have the budget for the 850 Evo, a cheaper SSD which still offers great speeds is the Sandisk SSD PLUS.
You can typically find a 240GB model for $69.99, and it also beats the 750 Evo by 35% in write speeds, with more consistent speeds overall. The 750 Evo is also beaten by the SSD Plus in other standard processes undertaken by an SSD such as random write and mixed I/O, where it holds a 61% and 46% average faster speed over the 750 Evo based on user benchmarks.
The areas the 750 Evo beats the SSD plus in are random read, random mixed IO and deep queue speeds, which are less relevant in general use, and are unlikely to be impactful.
http://ssd.userbenchmark.com/Compare/SanDisk-SSD-Plus-240GB-vs-Samsung-750-EVO-250GB/m25612vsm71929