Depends on what you're doing.
If you're just playing games and don't mind the "slow" speeds, don't bother getting one. I say slow in quotation marks because SD cards are already really fast and you won't notice much difference between the two.
The higher rated ones are more for professional work, like cameras recording (not just taking pictures, but videos) in 4K when constant high write speeds are needed.
Most consumer grade cards have low write speed, but great read speed. This is what most people will buy since it's cheaper and most will not need the constant high write speed professional cards have.
Obviously every manufacturer and SD card will be different, so your mileage may vary. All SD cards are not made the same. They're made within a margin of error.
tl;dr If you like throwing money down the drain for minuscule E X T R A performance, buy the professional grade SD card. It won't hurt anything but your wallet.