Only in usage. Both words have the same meaning: the 5th months of the year. Máj (from Latin MAIVS) is used in poetry, there is also a tight connection with May Day and the liberation in 1945. květen (from květ = flower) is used the same way like leden, duben, etc.
Apart poetry, the word "Máj" is only used when referring 1st May (První máj). As well "Apríl" is only used in czech in connotation with 1st April. :lol:
"Kviten" (as opposed to "květen") sound Ukrainian to me. Perhaps it may also be used in the Slovak-Ukrainian border regions (kde sa hutoria), but someone more knowledgeable than me would have to verify this.
This was an interesting thread because I didn't know the word Máj existed in Czech! I'm just wondering if you didn't see it written on a calendar, in which case it might simply have been Slovak?
Also in proverbs or sayings: "Máj, půjdeme v háj" Studený Máj, v stodole ráj. or in folk(?) songs "To bylo v háji, v měsíci máji, to bylo v háji zeleném. To bylo v háji, v měsíci máji, kdy láska hoří plamenem." Let us both consider poetry 8) It is quite common to print calendars in both Czech and Slovak. Czech Květen = Slovak Máj.