ADT(Android Development Tools):
at present Android The development tools used in the development are Eclipse, stay Eclipse compile IDE In the environment , install ADT, by Android Development provides upgrades or changes to development tools , It is simply understood that in the Eclipse Upgrade and download tools for development tools under .
adt It's just one eclipse Plug in for , It can be set inside sdk route     SDK(Software Development Kit):
Generally some are used by software engineers for specific software packages , software framework , hardware platform , A collection of development tools for establishing application software, such as operating system . stay Android in ,
SDK He provides developers with library files and other development tools . Simply understood as a collection of development kits , It is a toolkit used in the overall development
, If you don't Eclipse As your development tool , You don't need to download ADT, Download only SDK Can be developed .SDK You can compile it yourself , stay linux Through the environment make Order to proceed , It takes a long time , You need to be patient ... Then we can compile our own SDK adopt ADT Import eclipse. On this basis, the source code package can be modified , Such as modification android
system/app/phone.apk Source code in , Then call again make command , You can create new ones system.image file , This file is a mirror file .
android adt What is included :

android SDK contain :

Tools include :aapt tool ,adb,  database SQLITE  simulator emulator ,,fastboot, etc.

What matters is what you need for development android API