MP4 is a multimedia container format standard with the file extension .mp4
WebM is an open video encoding standard by Google
"The ogv version of the video seems to run a little better than the webm which itself seems to run better than the mp4"
from question "Controlling a HTML5 Video via offset-position ends in a performance fiasko"
"Probably webm will load faster than standard mp4 but i am not so familiar with webm format"
from question "WebM with VP9 vs MP4 with H.264 AVC which one is best overall"
"Also it looks like when i transcode webm to mp4 2.7 is 30 faster than webm"
from question "Ffmpeg performance issue when transcoding to webm"
"I tried mp4 and webm and sometimes the file size after i convert to mp4 is smaller than webm but it is also sometimes larger than the original file size"
from question "Best video format using ffmpeg converter"
"The mp4 implementation is more widely used and wouldn t require a webm fallback in most browsers"
from question "Google Chrome does not want to play mp4 using mediaelement.js"
|Usually more robust||
"Webm is usually more robust than mp4 which can be all over the place"
from question "HTML5 video loop doesn't work on Chrome (Sitefinity CMS)"