Both the TOEFL iBt and TOEFL PBT examine your knowledge of English in an academic setting. However, they have different formats.
TOEFL iBT measures reading, listening, speaking and writing skills and takes approximately 4½ hours. TOEFL PBT measures listening, structure (grammar), reading and writing and takes approximately 3½ hours.
As you can see, the iBT includes a speaking section, but the PBT does not. Unlike TOEFL PBT, the internet based TOEFL has no grammar section, although grammar is evaluated in Speaking and Writing responses. Your comfort in speaking English and grammar knowledge might affect which TOEFL test you choose to take.
Moreover, internet based TOEFL includes integrated tasks where students need to be able to combine their language skills in order to communicate effectively in the academic environments they plan to enter. The integrated tasks ask test takers to:
Scoring system is also different. The range of scores for TOEFL ibt is from 0 to 120points and the test results will be mailed to you 15 days after taking the test. PBT scores are between 310 and 677 points, and students receive a separate score for their Test of Written English (TWE). These scores are mailed five weeks after the test.
The cost of the PBT is US $140. However, the price to take the TOEFL iBT varies by country, between US $140 and $185.
Remember to evaluate your proficiency level in grammar, speaking and integrated skills before registering for a specific format.