to be simple 行业: industry, commercial undertaking that provides services e.g. the catering, hotel, tourist, entertainment, etc industry 饮食﹑ 旅馆﹑ 旅游﹑ 娱乐等（行）业. 工业: industry, manufacture or production , it's an idea corresponding to 农业 agriculture and 商业 trading business, excludes 服务业 service industry, too. e.g. Britain's coal industry 英国的煤炭工业 * heavy industry, ie producing large goods, eg steel or cars 重工业 产业: 1property , industrial enterprise e.g. 那些楼房工厂都是我的产业。 those buildings and plants are all my 产业. 2industrial e.g. industrial workers 产业工人 industrialization 产业化 tertiary industry 第三产业 企业 ： enterprise e.g. 企业家 enterpriser entrepreneurs enterprise culture 企业文化 实业: 实 is an idea corresponding to 虚。 实 means real, physical, 实业 includes all kinds of industries which produce physical products. so 实业 includes 工业， and certain service industries, such as catering industry. 业界： 业 means industry here..界 means circle, performing circle, academic circles, so 业界 means "in the circle of this industry"... e.g. 工商业界 in the circle of 工业和商业 the industry-standard method of encoding a document 业界标准的编制文档方法 三星仍保持业界第一 Samsung retained top spot

oh, I can write a essay about them....you need to pay me ;) haha