One of Citrix's strengths is that it has multiple products that can combine to deliver applications the user’s . Who can forget the tag line - deliver your applications anytime, anyplace, anywhere .. although it was often glossed over that printing from that application might be more character building than delivering it.

While this having a wide range of options is a "Good Thing" in that it doesn't tie you in to a specific solution - be that terminal services or hosted desktops - what options and considerations each solution brings to the party can be confusing. Which solution do you deploy - XenApp - or XenDesktop - is one "better" than the other? Are they mutually exclusive?

Citrix have recognised that determining the best technical solution for delivering applications to users can initially seem overwhelming. To this end, Jo Harder from Citrix Worldwide Technical Readiness has published a document Technical Guide to Application Delivery Option(s) for XenApp™ and/or XenDesktop™ that focuses on  the options that are available, as well as the criteria that should be used by architects and administrators when making your decisions.

The document covers features from Xenapp 5 & 6 and XenDesktop 4. Note also it is considering only the Platinum and Enterprise editions of these products.

Sadly, there is a glossing over of MS licensing requirement: but then this is about technical function considerations rather than a direct cost/feature comparison.

The document discusses the advantages (and restrictions) of Citrix streaming application processes; application delivery criteria and user profiles. It also touches on additional requirements such as auditing (Smart Auditor is only available in XenApp) and CPU/Memory control (again, xenapp only) whereas 3D Graphics support is only available for the desktop.

There are then gives a walkthrough scenarios giving some best fit considerations for a 3D application.,

While definitely an overview document - do not expect this to be a definitive guide on  'which is better to use for Scenario X Y or indeed Z' - it is an interesting read.

You can download the whitepaper from Citrix  from this link Technical Guide to Application Delivery Options for XenApp/XenDesktop  ( CTX125515)