These words, probably concocted in some business school, date from the 1970s. Both mean “to motivate or encourage.” Technically, they mean “to provide incentives.” The word incentivize is one of those noun-to-verb words formed by adding the suffix -ize. Its first cousin is prioritize.
The word incentive is a perfectly good noun.
The word incent has only one redeeming feature: it’s shorter.
Good writers avoid these words. Use motivate or encourage or provide incentives.
Example: The company’s new package of incentives should motivate the employees to put in longer hours.