Hi Stan, From 知乎： 上面很多人的解释太过诗意，却离真相比较远。所有离开居住地的行为，都可以称之为旅行。比如你出差去上海开个会，或者去纳斯达克敲个钟，都是旅行。只有围绕景点展开的活动，才叫旅游。周末开车去百花山，或者到塞班岛度个假，都是旅游。 国家旅游局不能叫国家旅行局。 This basically says that all actions that involve leaving the place you live, can be called 旅行. Eg. I'm going on a business trip to Shanghai; I'm going to the Nasdaq to take part in their IPO - both of these can be called 旅行. Only when you go to a place and travel around the area, can you use the word 旅遊. Eg., At the weekend I'm driving to Baihua Shan (to go sightseeing); I'm going to Saipan on holiday - both of these are 旅遊. The national tourist bureau is called the 旅遊局 and can't be called the 旅行局. 環遊 only every appears in the phrase "環遊世界", which means to go travel the World. Laurence

旅行的意思更加宽泛一些，可能是去玩也可能是去工干（比如商旅）。旅游就纯粹是出门游山玩水啦。

旅游 接地气老百姓都会说，日常用语 (number one option) 旅行 有点书面语，好温柔的味道, 抒情歌曲，散文用都很好。(used when you're writing a diary, or any a piece of writing) 环游 这个好高大上，想突出旅途经过很多国家，可以用。(often used when expressing our admiration or jealousy to other people's travel) 我自己很少用除了做梦： 我要环游世界。

Just add one more thing-"旅行" and "旅游" can be exchanged in many situations. But there are some fixed collocation. For "旅行", there are "短途旅行","长途旅行","旅行社"; and for "旅游", we have "旅游节","旅游局".

环游 can only be used combining with 世界. 环游世界 is pretty much a word so don't try to be smart and break it to parts. 旅游 and 旅行 are almost the same except 旅游 is more often used in speaking and the other in writing.