Buying an air-conditioner $1500 vs. $4000 with same BTU.?

Question:Does anyone know about air-conditioners? I'm living in Korea and I want to buy an A/C for my house. In Korea they are upright man-sized units with a separate outdoor <condenser>. The prices here vary a great deal, from $1500-4000 for the same BTU. Is there any difference in A/C technology or am I just paying for brand and style? Some of the more expensive are "signature series" and have automated cleaning "robots" and fancy hepa filters.

Answers:
Reckon it depends on what you want in your A/C ? Hepa filters are nice but how much does the filter cost when it comes time to replace it ? And what is automated cleaning robots ?
For the same BTU I think the answer is simple . Warranty !!