express-session和cookie-session的区别

Question

var express = require('express')  , cookieParser = require('cookie-parser')  , session = require('cookie-session')  , express_sess = require('express-session')  , app = express();//====================================================app.use(cookieParser())// app.use(session({ keys: ['abc'], name: 'user' }));// {}// { 'connect.sid': 's:cpI6_ewOlAoRIl0kGkwRVOOZAQnA0n_t.9Q1cv7SP1ADoHArxmqtqQEEXyQE// fRjaWxsXnQTY4bLI' }//====================================================app.use(express_sess({ secret: 'abc', key: 'user'}));// req.session: { cookie: { //      path: '/',//      _expires: null,//      originalMaxAge: null,//      httpOnly: true //    } // }// req.cookie: {user: 's:aJ97vKA5CCwxqdTj0AV1siRQ.fWusS5+qfCKICtwkfrzcZ/Gq8P0Qdx/kx8mTBhoOhGU'}app.get('/', function (req, res, next) {    res.end(JSON.stringify(req.cookies));    console.log(req.session)    console.log(req.cookies)});app.listen(3000);cookie-sessio 和express-session 的区别，和适用场合？