500
(historic period 1600-1750)/(fancily decorated) keyboard music is pre-pianoforte, so was (at first/before other things happened) written for organ or harpsichord/spinet etc. However, today it's possible to mistake it for Classical, as it's often done on piano. It tends to be quite beautiful and in strict time; there are often songs/dreamy mental states and everything is in harmony. There isn't much feeling of love, hate, guilt, etc. in the pieces. Listen to Bach, Scarlatti and Handel. A lot of "A" exam pieces are (historic period 1600-1750)/(fancily decorated).
Classical is mostly Mozart and Haydn, so listen to those. The pianoforte was new and interesting in their day so they were able to change/differ sound level much more than had been possible on the harpsichord. Pieces are in strict time and often phrases are repeated once loud and once soft; however the energetic/changing change is cool and controlled/not showy to our ears.
Romantic pieces often have rubato, (in other words) are not in strict time. There is great energetic/changing contrast and often the pieces tell a story or paint a picture, e.g. The Storm. there are some disagreements. Most 19th century composers are Romantic, so listen to Schumann, Liszt, Chopin. (Beethoven is on either side of Classical and Romantic, so doesn't really fit properly into either. )
how do you tell if its baroque romantic or classical