Both the statements actually imply that you were happy and took pleasure from the party you attended .
I would like to clarify this by giving definitions.
Google defines 'enjoy' as:
enjoy /ɪnˈdʒɔɪ,ɛn-/ verb
1. take delight or pleasure in (an activity or occasion).
I enjoy watching good films
Collins dictionary defines 'enjoy oneself' as:
Synonyms of 'enjoy oneself'
have a good time, be happy, have fun, have a field day (informal), have a ball (informal),live life to the full, make merry, let your hair down
Thesaurus.com defines 'amuse oneself' as:
amuse oneself
Main Entry: delight in
Part of Speech: verb
Definition: take pleasure from
Synonyms: admire, adore, amuse oneself, appreciate, be content, be pleased, cherish, dig*, eat up, enjoy, feast on, get a kick out of, get high on, get off on, glory in, groove on, indulge in, like, live a little, live it up, love, luxuriate in, relish, revel in, savor
All these imply that whether you say "I enjoyed..." or "I enjoyed myself somewhere" it simply means that you took pleasure from there.
Best Answer
As some of the comments have mentioned, it's not frequently used in English.
I would say that, unless it's being used in a humorous way, the phrase is usually reserved for fine dining settings. In other words, if a bachelor friend of mine was about to eat a bowl of hastily prepared Ramen noodles, or if I was about to eat a hamburger with my nephew at McDonald's, I don't think I'd say "Bon appetit!" – not unless I was trying to be a little humorous.
On the other hand, I might be more inclined to say it more seriously if I had just spent several hours working on a fancy meal. Even then, though, it's not a phrase I would utter very often.
In other words, you can say it, but I'd caution against overusing it.