Leviticus and Deuteronomy

The laws in Leviticus have a different purpose to those in Deuteronomy.

Those in Leviticus are for providing spiritual protection when a single person engages in a sin that would release powerful evil spirits into the nation. This was particularly true for sexual immorality and witchcraft. The culprit has to be dealt with severely to protect their neighbours from the evil. (Note: houses were burnt, not people).

The curses in Deut 28 relate to the nation and as a whole. If the entire nation turns away from God the curses are the consequence. They are what happens when the nation allows bulk access to the spiritual powers of evil.

More at Spiritual Protection before Jesus.