Virovskij Skorospelij (red) and Katja (pink)

I used to be unsecure if there were any other difference than color between the tomato varieties Virovskij Skorospelij and Katja. The are quite similar, just as early and vital. Katja jump started at sprouting, then they followed each other closely, until Virovskij Skorospelij flowered almost a week ahead of Katja. Today they ended up ripening on the same day. Virovskij Skorospelij might have slightly smaller tomatoes than Katja, but I´m not sure just from these first two tomatoes.
By the way, they are both russian heirlooms. Virovskij Skorospelij means The early from Virovsk, Katja is named after the elderly woman who still grow it in her Datcha on the shore of Lake Bajkal in Sibiria. You can almost catch a glimpse of it from the transsibirian railway.