Net Framework 4.0 和.Net Framework 4.0 Client Profile區別：
.Net Framework 4.0毫無疑問就像是.Net Framework 2.0一樣是.Net Framework 的 4.0版本；
而.Net Framework 4.0 Client Profile是.Net Framework 3.5 sp1的子集，是.Net Framework 4.0 簡化版，
是面向客戶端應用程序的（估計這也是為什么不能夠使用IIS7 API的原因）。
什么要引入這個簡化版本呢？
1. 減少.NET Framework以及包還.NET Framework的應用程序的部署時間；
2. 減少.NET Framework部署的失敗；
3. 減少.NET Framework在ISV軟件的所占大小，從而給其軟件更多的空間；
4. 減少安裝了.NET Framework Client Profile的系統受攻擊的“界面”，因為Client Profille中部包括ASP.NET和一些服務器所要的組件；
When to use NET4 Client Profile and when to use NET4 Full Framework?
Client Profile:
We recommend that the NET4 Client Profile be utilized as the primary framework for most client desktop applications (including Windows Forms and WPF apps).
Since we are considering to make the NET4 Client Profile available broadly to desktops via Windows Update, most client desktops may have NET4 Client Profile soon after NET4 releases making it ubiquitous*.
Until that time, NET4 apps can chain-install the NET4 Client Profile which is smaller and faster to install.
*Note: This plan is not final.
Full framework:
The Full framework is a superset of the Client Profile. It should mainly be used for:
Server apps (e.g. ASP.Net apps) For developer scenarios (for example, this includes msbuild) For all other legacy client scenarios (for example, this includes System.Data.OracleClient.dll which is being deprecated in NET4) that are not included in the Client Profile.