白话理解吧：
线程:操作系统的最小单位，是一串指令的集合。
进程：各种线程的集合，封装到一起，干事业！
进程与线程的区别？
- Threads share the address space of the process that created it; processes have their own address space.
- Threads have direct access to the data segment of its process; processes have their own copy of the data segment of the parent process.
- Threads can directly communicate with other threads of its process; processes must use interprocess communication to communicate with sibling processes.
- New threads are easily created; new processes require duplication of the parent process.
- Threads can exercise considerable control over threads of the same process; processes can only exercise control over child processes.
- Changes to the main thread (cancellation, priority change, etc.) may affect the behavior of the other threads of the process; changes to the parent process does not affect child processes.
翻译下：
线程是执行的指令集
进程是资源的集合
线程共享内存
进程独立内存
线程启动速度开
进程启动速度慢
线程之间直接数据直接交流
进程之间直接数据不能直接交流
一个线程可以操作其他线程（同一进程）
进程只能操作子进程
主线程的修改会影响其他线程
主进程的修改，不会影响其他子进程
线程与线程之间没有实际的立足关系
主进程死亡，其他进程就会死亡
就这些，用起来理解就行。