I've been asked to write a comparison between Photoshop Creative Suite and Photoshop Elements. I've actually never used Photoshop Creative Suite. However I have been learning digital painting from tutorials (by Oatley Academy and Ctrl Paint) that teach using Photoshop CS.
I have been using Photoshop Elements because it came as a free download with my pen tablet. You can buy Photoshop Elements for a reasonably cheap price as a one time download where as for Photoshop CS (now Photoshop CC) you must buy a monthly subscription. This will end up costing quite a lot in the long run, but you will always have the most up to date version. So the main benefit to using Elements is the price.
Elements does have a lot of the same tools that CC has. It is basically a pared down version of CC. While I have been learning digital painting I have encountered a few roadblocks with Elements. It does not have certain tools or capabilities that CC does that I would find useful.
Canvas Rotation Tool
I found that drawing smooth lines and brush strokes to be very difficult in Photoshop. The ability to rotate the canvas is an important tool for achieving smooth lines. Unfortunately, Elements' canvas rotation tool is quite limited and you can only easily rotate the canvas 90 degrees at a time. With Photoshop CC (from what I understand) you can easily rotate the canvas at any angle. You can rotate at smaller increments in Elements but it is awkward and it also creates problems with the image when you straighten it again. the different layers will not register properly.
The warp tool is a handy tool in CC that enables you to manipulate a selection. It is similar to the transform tool but it gives you much more control. The warp tool is especially important if you are going to be using photo textures in your artwork and you want them to wrap around painted objects.
Elements only has the transform tool. With the transform tool you can only manipulate the selection in a straight path. To manipulate the selection in a rounded way the warp tool is necessary. If you want to use photo textures and you are creating a relatively flat or collage style of art, the transform tool is probably all you would need.
Elements does not have the ability to group layers together. Layer groups are important for organization. They also give you the flexibility to be able to work on the layers in the group either separately or as a whole. The more complex your paintings get the more likely you will require the ability to group layers. Having your painting well organized and using layer groups in a logical way will be especially important if you need to make changes at a later stage. This could be important if, for example, you need to satisfy a client or an art director.
If you are using photo textures, layer groups can become important if you need to patch together pieces of photo texture to cover an area. It will enable you to make the overlapping areas blend together better.
You will also require the ability to group layers if you want to create masks within masks.
There are so many things you can do in Photoshop. It can be quite baffling when you are starting out to figure out what the tools do and how to use them for digital painting. You will most likely only use a fraction of the tools available. Some artists limit themselves to only a few tools and yet they create amazing artwork. Having more tools does not necessarily mean you will create better artwork. Photoshop Elements has less tools than Photoshop CC. That said, there are still many tools that I have not yet tried.
Good luck in your digital painting endeavors.