This isn't about collocations or even about business - it's about countable and uncountable nouns. Remember that the noun 'travel' is uncountable, so you can't say 'a business travel' or 'business travels'. This is because 'travel' cannot be an individual event. 'Travel' is abstract : a concept, an activity or sector. For example, you could say 'This airline specialises in business travel' or 'Business travel accounts for a large proportion of our annual expenses.' 'Trip' is countable. A trip is an event on a specific occasion - the same as a journey, a break, or a holiday. You can say 'a trip' to refer to a single event, or 'trips' to refer to several individual events : for example 'Julia went on a business trip to Paris last week' or 'Julia went on a lot of business trips last year'. I hope that makes sense.

business travel is more general.. like business expenses (several) e.g. 'Business travel is the part of my job I hate' business trip refers to a specific occasion.. like A business expense (one) e.g I have a business trip next week.

Thank you very much for your explanations.