HTC doesn't plan to release the One M9+ in the US and Europe
What's different is that the One M9+ features a 5.2-inch display with 1440 x 2560 pixels (as opposed to the 5-inch 1080p screen of the M9), a physical home button that includes a fingerprint scanner, a Duo rear camera, and an octa-core 2.2 GHz MediaTek MT6795T processor.
But will the M9+ be a China-only device? Well, the handset might be available in other (unspecified) markets, but the US, Canada, and Europe aren't among them. HTC stated that "the One M9+ is not currently planned to be released in North America or Europe, where we believe our flagship HTC One M9 is the best choice for blazing fast performance, incredible sound, and network compatibility across the broadest range of operators."
So it looks like HTC isn't yet ready to launch a Quad HD handset in the US, despite the fact that rivals like Samsung, LG, and Motorola all have such devices on sale. Or maybe HTC is readying a surprise for later this year? Only time will tell.