The two versions differ in internal details like the indexing system, optimizer, and storage engine.
这两个版本在内部细节上不同，如索引系统、优化器和存储引擎。
2
A workflow system consists of two parts; a workflow specification tool and a workflow execution engine.
工作流程系统包括两个部分：一个工作流程指定工具，一个工作流程执行引擎。
3
Also, I ended up writing my own e-commerce engine with a template processing engine and built-in database system; then I spent nearly two years working on it.