They have a similar meaning but are used in different contexts. ‘enlarge’ tends to imply a permanent or long term change, while expand may be for a short time, is reversible, or just momentary. However, sometimes this distinction is not evident, and the two are interchangeable. ‘The company has expanded its range of products’ ‘The business has been expanding for some years’ ‘The scan shows that the patient has an enlarged liver’ ‘When his family arrived he enlarged his house’ ‘This fabric will stretch so the clothes are expandable - they will fit all sizes.’ ‘There is a small gap to allow for expansion of the rails in hot weather’