Smaller Screen, Different Resolution
If you've seen the Samsung Galaxy S6 in person you know that its 5.1-inch display with Quad HD resolution is absolutely stunning. If you haven't seen it and can't go see it right now, take DisplayMate's word for it. The Galaxy S6 display is, hands down, one of the best smartphone displays on the market.
Apple's iPhone 6s display probably won't come with Ultra HD resolution and rumors don't point to a Quad HD display either. Instead, it's looking like we'll get more of the same from Apple.
iPhone 6s rumors have, up to this point, hinted at two display sizes. A 4.7-inch iPhone 6s to replace the iPhone 6 and a 5.5-inch iPhone 6s Plus to replace the iPhone 6 Plus. They've also started to point to the screen resolution.
According to The WSJ "Apple is expected to keep the screen resolution about the same" as the previous models. This is good if you're fine with the Retina HD displays on the iPhone 6/iPhone 6 Plus, bad if you were hoping for Quad HD like the Galaxy S6 or Ultra HD.