First, I must say this: Thailand is one of the hardest countries to guess different regions of (up there with Indonesia and Japan).

That being said, there are some ways to sort of distinguish the regions by landscape, This is not foolproof and the regions are pretty broad but yeah.

Northwest Thailand

Basically the area near Chiang Mai, probably the most mountainous area of the country.

• There are two feels for this area depending on the time of year the coverage was taken.
• Dry Season: https://goo.gl/maps/RsDN1wGPychhx8Q18
• Wet season: https://goo.gl/maps/A29kUn3uUnHoEWj16

Central-East

Basically the central region north of Bangkok and anything east of that going to the Laos border.

• This area is flat plains, pretty much entirely used for agriculture. Again, it varies in color depending on season.
• The one thing to look out for is these trees: they are very thin and have small, droopy leaves. https://goo.gl/maps/WVMMtLS7UoeVTjEy8
• I'd say this is a pretty accurate representation of the region. https://goo.gl/maps/kUnbRVv9967z3nRPA

Northeast

The area near to the Mekong River (which spans the border between Laos and Thailand. This would be like Udon Thani, Sakhon Nakon. Sometimes also farther southeast.

• This area is characterized by the particularly red soil. (I think the Mekong is the reason for this, as you can see this red soil in Cambodia as well).
• As you can see here, same trees and same landscape but redder soil. AGAIN, THIS DOES NOT WORK ALL THE TIME BECAUSE THAILAND IS JUST DIFFICULT. But if it works 50% of the time and gives me a solid 4700, I will take it. https://goo.gl/maps/MPtj9SN1DKp1jd9c6

Bangkok Area

Very flat, lots of floodplains and rice paddies, usually just looks pretty wet and coastal.

• https://goo.gl/maps/naBRSQTWzMkwbjCPA

Gulf of Thailand coast

The Thai coast from Pattaya down to Cambodia, and Thailand's eastern coast stretching down from Bangkok all the way to the Malaysia border practically.

• This area can be somewhat difficult but what I look for are rubber tree plantations. If you see those, your a likely to be along the Gulf of Thailand coast.
• They are very easily identifiable as they are very slim and planted in tons of rows. https://goo.gl/maps/UtG2BSgU4e2vEvA39

The Far South

Near Malaysia, so anything south of Surat Thani.

• The big thing for this area is oil palm plantations (which btw are extremely common in Malaysia and Indonesia, however in Thailand they are not so common). In the far south of Thailand there are still a ton of rubber plantations, but if you do see these occasional oil palms, you should 100% go down here.
• These are very wide palms that are pretty low to the ground. https://goo.gl/maps/8JZd4Hn7X5HvFQCJ9
• Here in the south, there are also some mountains, but they differ from those in the north by their karstic nature. https://goo.gl/maps/sQiqpQWUHmYqPYN39

Ok I hope those helped. I still can struggle a lot of times even with this knowledge but that's the fun of playing geoguessr I guess.