TOEFL - You will have 3 - 5 reading selections of twenty minutes each. Reading materials are academic in nature. Questions are multiple choice.
IELTS - 3 reading selections of twenty minutes each. Materials are, as in the case of the TOEFL, related to an academic setting. There are multiple type questions (gap fill, matching, etc.)
TOEFL - The listening selection very different from the IELTS. In the TOEFL, you will have 40 - 60 minutes worth of listening selections from lectures or campus conversations. Take notes and respond to multiple choice questions.
IELTS - The largest difference between the two exams is in listening. In the IELTS exam there are a wider variety of question types, as well as exercises of differing lengths. You will answer questions as you move through the listening selection of the test.
TOEFL - Two written tasks are required on the TOEFL and all writing is done on the computer. Task one involves writing a five paragraph essay of 300 to 350 words. Note taking is important as the second task asks you to take notes from a reading selection in a text book and then a lecture on the same topic. You are then asked to respond using notes by writing a 150 - 225 word selection integrating both the reading and listening selection.
IELTS - The IELTS also has two tasks: the first a short essay of 200 - 250 words. The second IELTS writing task asks you to look at an infograhic such as a graph or chart and summarize the information presented.
TOEFL - Once again the speaking section differs greatly between the TOEFL and the IELTS exams. On the TOEFL you are asked to record responses on the computer of 45 - 60 seconds to six different questions based on short descriptions / conversations. The speaking section of the test lasts 20 minutes.
IELTS - The IELTS speaking section lasts from 12 to 14 minutes and takes place with an examiner, rather than a computer as on the TOEFL. There is a short warm up exercise consisting mainly of small talk, followed by a response to some sort of visual stimulus and, finally, a more extended discussion on a related topic.