IELTS general module is tailor made for potential immigrants to English speaking countries whereas IELTS academic is made for students who are applying to universities and colleges in these English speaking countries.
Among the four different parts of the IELTS examination both potential immigrants and academic aspirants will have the same listening and speaking modules.
The reading and writing modules are different for academic and general modules. The reading in the academic is completely based on passages that are based on academic subjects whereas reading in general module of the IELTS is different as it has passages based normal day today situations, situations in industrial places and even subjects off general interest. The writing module in the academic and as well as in the general module require the test taker to write an essay. However the other task in the writing section is different for both the academic as well as the general modules. The academic module will present you some data in graph, diagram, chart, table, or a map. The test taker will have to present the data, or even interpret the data. The general module will require you to write a letter instead of this task.