Video looks better in export window than actual mp4 exported video

I'm using the Youtube 1080p HD export preset and everything looks fine in the export video that shows me what it will look like, but when the video is rendered and exported it is way blurrier and text/details/ lines in general are thinner. Also I'm not sure if this is relevant but when I pasue and play in the viewport when editing, the less detailed version shows up while playing and than when paused to a stop it goes back to blurry and thin, even though my playback resolution is set to full. Thanks!