What are the differences Between Individuallized Education Plan and individualized Transition Plan?

Answer 1

Hope this helps, it comes from the US Dept. of Education IEP Guide:

Transition Services

Transition refers to activities meant to prepare students with disabilities for adult life. This can include developing postsecondary education and career goals, getting work experience while still in school, setting up linkages with adult service providers such as the vocational rehabilitation agency--whatever is appropriate for the student, given his or her interests, preferences, skills, and needs. Statements about the student’s transition needs must be included in the IEP after the student reaches a certain age:

Transition planning, for students beginning at age 14 (and sometimes younger)--involves helping the student plan his or her courses of study (such as advanced placement or vocational education) so that the classes the student takes will lead to his or her post-school goals.

Transition services, for students beginning at age 16 (and sometimes younger)--involves providing the student with a coordinated set of services to help the student move from school to adult life. Services focus upon the student’s needs or interest in such areas as: higher education or training, employment, adult services, independent living, or taking part in the community.

Answer 2

An IEP is a yearly plan for special needs students who have been determined to need extra help from other professionals, speech, occupational therapy, physical therapy, hearing or vision specialist etc. It sets goals and objectives and can be revised at any time by parent or school team who can call a meeting and make changes.
A transition plan happens, also with special needs kids from preschool to kindergarten and then again at 14yrs. More forms and assessments. For those going into H.S there is an interview to see what the youngster knows about adult life, goals, services or additional help needed for independent living.
Hopefully a preschool teacher will expand on the younger one.. I don't teach little guys