A Deacon is ordained and is lowest position , after training
in theology the person is ordained as a deacon, and this is for one year. after the year they are ordained as a priest.
You can tell if someone is a Deacon as they wear the stole across the chest ends tied together and when they become a priest this is worn like a scarf around the neck with both ends hanging down. A deacon works as a curate with a vicar or rector for the year, and then works way up to get own parish. Hopes this helps.
A further piece of information at a high mass when 3 priests celebrate the deacon wears stole across chest this is because deacon is an assistant,