Often Windows CE, Windows Mobile, and Pocket PC are used interchangeably. This practice is not entirely accurate. Windows CE is a modular/componentized operating system that serves as the foundation of several classes of devices. Some of these modules provide subsets of other components' features （e.g. varying levels of windowing support; DCOM vs COM）， others which are mutually exclusive （Bitmap or TrueType font support）， and others which add additional features to another component. One can buy a kit （the Platform Builder） which contains all these components and the tools with which to develop a custom platform. Applications such as Excel Mobile/Pocket Excel are not part of this kit. The older Handheld PC version of Pocket Word and several other older applications are included as samples, however.

　　Windows Mobile is best described as a subset of platforms based on a Windows CE underpinning. Currently, Pocket PC （now called Windows Mobile for Pocket PC）， SmartPhone, and PocketPC Phone Edition are the three main platforms under the Windows Mobile umbrella. Each platform utilizes different components of Windows CE, as well as supplemental features and applications suited for their respective devices.

　　Pocket PC and Windows Mobile is a Microsoft-defined custom platform for general PDA use, and consists of a Microsoft-defined set of minimum profiles （Professional Edition, Premium Edition） of software and hardware that is supported. The rules for manufacturing a Pocket PC device are stricter than those for producing a custom Windows CE-based platform. The defining characteristics of the pocket pc are the digitizer as the primary Human Interface Device and its extremely portable size.

　　The SmartPhone platform is a feature rich OS and interface for cellular phone handsets. SmartPhone offers productivity features to business users, such as email, as well as multimedia capabilities for consumers. The SmartPhone interface relies heavily on joystick navigation and PhonePad input. Devices running SmartPhone do not include a touchscreen interface. SmartPhone devices generally resemble other cellular handset form factors, whereas most Phone Edition devices use a PDA form factor with a larger display.

　　Windows Mobile 5 supports USB 2.0 and new devices running this OS will also conform to the USB Mass Storage Class, meaning the storage on PPC can be accessed from any USB-equipped PC, without requiring any extra software, except requiring a compliant host. In other words, you can use it as a flash drive.

　　关于Windows Mobile

　　Windows Mobile,是 Microsoft 用于 Pocket PC 和 Smartphone 的软件平台。Windows Mobile 将熟悉的 Windows 桌面扩展到了个人设备中。Windows Mobile是微软为手持设备推出的"移动版Windows",使用Windows Mobile操作系统的设备主要有PPC手机、PDA、随身音乐播放器等。Windows Mobile操作系统有三种，分别是Windows Mobile Standard、Windows Mobile Professional,Windows Mobile Classic.目前常用版本Windows Mobile 6.1,的版本是6.5.

　　关于Windows CE

　　Windows CE作业系统是Windows家族中的成员，专门设计给掌上型电脑（HPCs）所使用的电脑环境。这样的作业系统可使完整的可携式技术与现有的Windows桌面技术整合工作。 Windows CE 被设计成针对小型设备（它是典型的拥有有限内存的无磁盘系统）的通用操作系统，Windows CE 可以通过设计一层位于内核和硬件之间代码来用设定硬件平台，这即是众所周知的硬件抽象层（HAL）（在以前解释时，这被称为 OEMC （原始设备制造）适应层，即 OAL; 内核压缩层，即 KAL. 以免与微软的 Windows NT 操作系统 HAL 混淆） .