Broad match allows your keywords to run on search terms that are relevant variations to your keywords, even if they aren’t in your keyword lists. Broad match keywords can contribute to a lower overall CTR in some cases if they appear relevant for too many search terms.
Phrase match lets a keyword trigger only when someone searches for your exact keyword phrase or close variations of your exact keywords. It can increase the likelihood of a click since it shows your ad only when it matches the phrase the searcher typed in.
Exact match will only show your ad to customers who are searching for your exact keyword or close variants. It gives you most control over who sees your ad and gets a higher CTR, but may yield lower overall impressions.