The main difference between Tide Original and Tide Simply Clean is the Tide Simply Clean is a more watered down version of Tide Original.
Tide Simply clean is cheaper than original Tide so if you want the same cleaning power of Tide Original but cannot afford original Tide laundry detergent then getting Tide Simply Clean will be okay and work just as good.
Tide Original has a better scent to it though and leaves your clothes and laundry smelling much better after washing it than the Tide Simply Clean does.
I used both Tide and Tide Simply Clean and they both did a good job at cleaning the clothes.
If I had not enough money I would just go with Tide Simply Clean.
But there's not much difference between the two other than Tide Simply Clean has more water than it does soap and that makes it cheaper and it has a different name.