@Mark ******
When you apply for those visa outside Thailand, many differences are there, but significant ones may be,
- Non-OA: multiple entries, entry stamp for 365 days on every entry, the visa itself is valid for 1 year from the issued date. You need to have specific insurance when applying for a visa and in case you want to apply for an extension from Non-OA entry.
- Non-O: single entry, entry stamp for 90days, the visa itself is valid for 90days from the issued date. You may or may not need specific insurance.