noun
satsuma mandarin; mandarin orange; tangerine
Refers specifically to the common Japanese mandarin (Citrus unshiu), a seedless, easy-to-peel citrus fruit. Often eaten fresh in winter.
冬になると、こたつでみかんを食べるのが楽しみです。
In winter, I look forward to eating mandarins under the kotatsu.
この
These mandarins are sweet and delicious.
noun
citrus fruit (general)
Broadly refers to citrus fruits of the genus Citrus. In everyday speech, みかん usually means the satsuma mandarin; this broader sense is more technical or contextual.
みかんの仲間には、オレンジやレモンなどがあります。
Relatives of the mandarin include oranges and lemons.