Managed dedicated web hosting is for an individual or company that wants storage and bandwidth without the restrictions. If you have a site which you want to have more bells and whistles programmed into it, then managed dedicated hosting is the way to go. When you are running web applications over 1,000GB, that's when you should consider stepping up your Dedicated web hosting package.
There are various types of web plans based on the types of internet applications that you are developing for your business. For example, if you are developing online streaming video content for your site, then you might want to go past the 1000GB limit on your account and get more bandwidth. Managed Dedicating hosting means your provider takes complete or near complete care of your server. It include anything from basic system maintenance and patches to applications maintenance, security, monitoring, etc. Managed Hosting Services are used primarily by companies that either don't have staff with the expertise to manage a dedicated server or don't have staff with the time to attend to the needs of managed hosting.
While exact definitions vary among providers, generally speaking managed to host means your provider takes complete or near complete care of your server. It can include anything from basic system maintenance and patches to applications maintenance, security, monitoring, etc.
Someone that needs to be dedicated hosting and wants to rely on their host for pretty much anything and everything regarding their server needs to strike a relationship with a managed service provider.
Full blown managed services involve lots of skilled people hours. Not only that, since every managed customer is unique, it's hard for a managed provider to be overly systematic. For this - expect to pay a great deal more than today's budget server provider but if your needs demand it, and you choose a solid provider it should be money well spent.
Unmanaged dedicated hosting obviously refers to dedicated servers with less, little or none of the skilled people support you would expect to find in managed. You sign-up, you pay, and in a few minutes to a few hours you get a welcome email with IP address, login, FAQ's, etc. - Beyond that, you are pretty much on your own. Relax - you are not as own your own as it seems.
First off, most unmanaged providers do in fact offer technical support, and most that we've seen is very good. If you choose unmanaged dedicated service, you do need to have someone on your team that knows the technical side a good bit, but they do not necessarily have to be experts. While you may have to wait for 12 - 24 hours or you may even have to pay extra for it, nearly all the unmanaged providers I know do have high-level techs available to handle serious issues. Also, most providers give some immediate reboot service. Unless you have been tinkering with some critical configuration files or have a hardware failure, a reboot can help with a range of issues.
Lastly, unmanaged providers may not support you or whatever you put on your server after you move in, but they do stand by the hardware and software they sell you. If a hard drive crashes they are going to replace it for you (although you had better be doing your backups) and if your system crashes most fix it for you.