@Kayleen ****
There is no ETA. There is Visa on Arrival. This is for a specific list of countries that can APPLY for and PAY for a 15 day visa at the airport.
There is visa exempt, which is for a much larger list of countries. These people don't get any visa, they get a visa exempt entry stamp for 60 days.
There is visa waiver, which is a bilateral agreement between countries. This is anywhere from 15-90 days depending on what country your passport is, and is also not a visa.
YOU don't get to choose. You qualify for one of them.