MAJOR DIFFERENCES BETWEEN THE IELTS AND THE TOEFL Reading

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.)

Listening
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.

Writing
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 infographic such as a graph or chart and summarize the information presented.

Speaking
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.

Important Related Resources
Free TOEFL Exam Preparation
Free IELTS Exam Preparation
TOEFL - Test of English as a Foreign Language
IELTS - International English Language Testing System