Devices without an HTML Web browser use WAP browsers, which are far more limited in terms of what they can display. Devices with WAP browsers are generally also far more limited in terms of memory, which disallows them from showing the full range of content on most Web pages...or they just end up formatting them differently to allow them to display on a phone screen. With an HTML browser, you'll generally get a rendering of a Web page that's more akin to what you'd see on a desktop computer, although certain types of media may display differently or not at all. For instance, if you go to YouTube on a desktop computer, then you'll be able to watch the videos inline on the page. On a mobile device, however, you'll generally need to click on a link that launches the video in the device's built-in media player. Still, HTML browsers are far superior to WAP browsers, so I'd definitely recommend an HTML browser if you do a lot of Web browsing.
By the way, be sure to use the user reviews on Verizon Wireless' Web site to research phones prior to making a purchase. Read up on the Glyde, because - as much as I wanted to like the phone - it has a high probability of being problematic for you.