Difference between Xen hypervisor and Xen server
I was confused too. I'm scrambling to leave VMWare ESXi baremetal hypervisor for various reasons.. most of which have to do with the lack of configurability in the free/lab version of ESXi.
XenServer - XenServer is an enterprise-class, cloud-proven, virtualization platform that delivers all of the critical features needed for any server and datacenter virtualization implementation.
XenProject - See this table for a list of features across differing versions of their hypervisor : http://wiki.xenproject.org/wiki/Xen_Release_Features
XenProject Hypervisor's getting started : http://wiki.xenproject.org/wiki/Getting_Started
The recommended way for most people to get Xen Project is to install via your distribution wherever possible. There are many distros which have good support for Xen Project included right out of the box....
Different people say differing things.. is XenProject Baremetal?
From : http://www.webhostingtalk.com/showpost.php?p=8374801&postcount=23
In the case of two commonly used bare metal hypervisors (VMWare and Hyper-V), these are special cases in which both the hypervisor and the special management O/S are provided by the same company. In this case, since the same company provides the entire "stack", they can offer an ISO that installs the lot.
Xen is different - as a previous posted mentioned, it's a "project" rather than a "product" - I'm not sure you understood the point that was being made. Xen is the hypervisor and a set of management tools that run within the special guest O/S (which Xen refers to as "dom0"), but Xen themselves do not supply that operating system themselves. I think there are two reasons for this - 1) There are many other suitable operating systems already in existence, so why re-invent the wheel? and 2) Different people will have different preferences as to which operating system they prefer, so why force them into a single option when you can provide choice?
So, what makes Xen different from other bare metal hypervisors:
Pros: - You have a choice of different operating systems to run for the management layer. This allows people with expertise in various O/S's to choose the most appropriate one and allow them to fine-tune it as appropriate. - This allows Xen to focus on doing a single thing - building a hypervisor and associated tools, without being distracted by building a custom O/S to run with it.
Cons: - There is no single vendor or pre-packaged solution/product that you get with VMWare or Hyper-V. In theory, someone could package up a linux or BSD distro with all the Xen tools into an installable ISO, but the question would be - which O/S and why? Then you'd also have the issue that you'd be combining different packages/distros that may have different licencing or distribution rights, different update mechanisms etc. So, while it's possible to build an installable ISO, it's probably more hassle than it's worth.
So, in summary - if you want a pre-packaged solution that you can install "with my eyes closed" - Xen is probably not your best choice. However, if you want something that can be extensively customised/tweaked and finely tuned then Xen is probably a better choice than VMWare or Hyper-V.
Hope all this makes sense.
In the end do you want to administer Xen Hypervisor with a certain privileged OS? or let Citrix pick for you and get Xen Server?
Sources :
http://www.xenproject.org/developers/teams/hypervisor.html
http://www.xenserver.org/overview-xenserver-open-source-virtualization/open-source-virtualization-features.html
I did some further digging since I was confused myself. According to the Xenserver.org website, the XenServer distribution is based upon:
XenServer is a Linux distribution that is based on the Xen hypervisor, the Linux kernel, and the CentOS Linux distribution and user tools.