Unless you go on to do chemistry at degree level, the difference between the two terms isn't likely to worry you. However, the difference is small, and negligible compared with the differing values for lattice enthalpy that you will find from different data sources. In fact, there is a difference between them which relates to the conditions under which they are calculated. Lattice enthalpy and lattice energy are commonly used as if they mean exactly the same thing - you will often find both terms used within the same textbook article or web site, including on university sites.
