My encounter with Progressive rock happened in high school, when I first got exposed to British bands like King Crimson, Genesis ['Selling England by the Pound' album era, I used to be -and still is- obsessed with the track "Firth of Fifth"], Caravan, Yes etc.
I then found out about some really good progrock bands from France, and started digging into it.
Last summer, I came across an antique sell in the streets of Grenoble. People would sell old antiques, vinyls included. I found a LP by the band Ange, a famous progressive French band in the seventies.
You will therefore appreciate different styles within the same genre of music, produced in the same timeframe.
Check this greatness: