Answer: Hybrid teas produce their flowers mostly one bloom to a long stem, grow 3'-6' high and tend to be open rather than bushy, with long, straight, upright canes. Floribunda roses offer flowers in abundance, with the blooms borne in large clusters on a single stem. They are compact shrubby plants, growing 3'-5' high. Grandifloras suffer from an identity crisis as a class in that they are a tall hybrid with large flowers on long stems like a hybrid tea, but their long stems grow in clusters, like a floribunda.
For even more information about the confusing array of roses available to gardeners, consult the book "Roses for Dummies" by IDG Books (ISBN# 0-7645-5031-4) - it contains a wealth of information!
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