PhotoShop Comparison

I suspect that most professional illustrators and digital artists use multiple applications, but will almost certainly include Photoshop.  For free hand digital art try Krita, which is free, and Paintstorm Studio which cost $19 when I bought it.  Both those apps have fantastic brush engines and are a lot of fun.

If you are using a Windows PC take a look at Lazy Nezumi Pro, which is the best Photoshop addon for tablet users bar none IMO.

If you are more interested in Photoshop for illustration then check out Bert Monroy's YouTube content.  Bert is the original Photoshop artist and has a ton of incredible tips and tricks that make your life easier and your work better.  If you only check out one of my links, make it this one.  It could change your life.

www.youtube.com/c/BertMonroyArtist/videos

Photoshop is the leading image editor application for photos. It can also be used to create painted artwork. There are many examples of artwork created in Photoshop if you do a search on the web. However, most people do not consider Photoshop to be an easy to learn application. 

You can do artwork in Illustrator. Usually Illustrator artwork is flatter with solid areas of color and does not look as painterly as artwork created in Photoshop, although there are acceptions. Most people consider it to be easier to edit artwork in Illustrator than in Photoshop.

As far as low cost and free applications, this article has some suggestions. https://www.reviewgeek.com/1472/6-cheap-alternatives-to-adobe-photoshop/ I can't vouch for them personally because I haven't used them.

Adobe offers Photoshop Elements which is an excellent value and does most of what Photoshop can do. It is $100 and does not require a subscription. It might be worth it for you to get the trial version and see what you think.

" Are there other programs which are low cost or free and better quality than those mentioned above to learn on?"

I do not think so, low cost is low cost for reason.

"I would like to know if this program can be used to do digital artwork in the same format as painted artwork?"

Yes, many (read most) digital artists use Adobe Photoshop for digital artwork.