How does a tourist visa differ from an exempt stamp during immigration in Thailand?

Yes

Just because you bought a tourist visa from a Thai embassy/consulate does not automatically mean immigration will let you into the country. The fees are not refundable so the embassy doesn't care.

The contact? The conversation might not be much different, assuming your travel history is fine.

Unlike what most of others in this group are telling you though, having a visa makes ALL the difference with regards to your likelihood of getting in. Without a visa the check whether you have not already stayed enough time in Thailand as a tourist comes on the IO. With a visa this check comes on the embassy. The visa means: you have permission to enter the country.

Immigrations officers can still deny entry, like a security officer at an Ed Sheeran concert being able to refuse entry if you show up with a chain saw around your neck. But they're not supposed to refuse entry based on travel history. That check has been done. That's why immigrations officers tell people who approach the end of their reasonable time in the country as a tourist to get a visa: it's so that you know upfront whether you can enter. Why would they advise this if it made no difference and your likelihood of getting refused were the same?

There are some severe misconceptions with the established crew in this group and this unfortunately is one.

Yes

No difference, they are looking at total number of days you stayed in Thailand during the year and how many times you left for a day and came right back.

No

If you have a tourist visa they don’t even look at you, only looking for visa dodgers getting exempt stamps 😛😛

Not really. They look more at your history

no difference. There looking at other things like stay history and even the way your dressed.

More info required

Make a difference for what?