楓と紅葉は、同じ「カエデ」に分類される植物の呼び名で、厳密な決まりがある訳ではないようです。紅葉を観賞するようになったのは平安時代頃からのようで、「紅葉を見て夏に疲れた体に生気を取り込む」という中国の思想が伝わったことがきっかけになったという説があります。

The terms "kaede" (楓) and "momiji" (紅葉) both refer to plants classified under the broader category of "maple." It appears that there are no strict rules governing the use of these names. The appreciation of autumn foliage, or "momiji," became popular around the Heian period. It is said that the influence of Chinese thought, which emphasized revitalizing the body tired from summer by observing the changing colors of autumn leaves, played a role in sparking this trend.

Obi fabrics with this Japanese pattern from the obico selection