Teach, instruct, educate, train, discipline, school are comparable when they mean to cause to acquire knowledge or skill.
Teach implies a direct showing to another with the intent that he will learn; it usually suggests the imparting of information, but in addition it often also connotes the giving of help that will assist the learner in mastering such difficulties as are involved in putting the new knowledge to use or in making it a part of his mental or physical equipment.
Instruct stresses the furnishing, especially the methodical furnishing, of necessary knowledge or skill to someone else.
Educate , although it implies or presupposes teaching or instruction as the means, stresses the intention or the result, the bringing out or development of qualities or capacities latent in the individual or regarded as essential to his position in life.
Train , even when it is used as a close synonym of educate , almost invariably suggests a distinct end or aim which guides teachers and instructors; it implies, therefore, such subjection of the pupil as will form him or fit him for the state in view.
Train is especially employed in reference to the instruction of persons or sometimes animals who must be physically in excellent condition, mentally proficient, or quickly responsive to orders for a given occupation or kind of work.
Discipline , even more than train , implies subordination to a master or subjection to control, often self-control.
School is sometimes interchangeable with educate or with teach or instruct , but it is more often used in the sense of train or discipline , frequently with the added implication of learning to endure what is hard to bear.