Will Apple TV stream HD or SD Xfinity?

Xfinity offers this App

XFINITY Stream on the App Store

Apple TV - Technical Specifications - Apple

is capable of the following resoltions

H.264 video up to 1080p, 60 frames per second, High or Main Profile level 4.2 or lower

H.264 Baseline Profile level 3.0 or lower with AAC-LC audio up to 160 Kbps per channel, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats

MPEG-4 video up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats

If I buy the cheapest SD package from Comcast can I watch HD channels on my Apple TV? Yes I have a HD tv, I’m just trying to save money.