Yes they share the same continental plate. But:
"There is a significant variance for GDP (PPP) per capita within individual EU states, these range from €11,300 to €69,800 (about US$15,700 to US$97,000). The difference between the richest and poorest regions ranged, in 2009, from 27% of the EU27 average in the region of Severozapaden in Bulgaria, to 332% of the average in Inner London in the United Kingdom. On the high end, Inner London has €78,000 PPP per capita, Luxembourg €62,500, and Bruxelles-Cap €52,500, while the poorest regions, are Severozapaden with €6,400 PPP per capita, Nord-Est with €6,900 PPP per capita, Severen tsentralen with €6,900 and Yuzhen tsentralen with €7,200."
https://en.wikipedia.org/wiki/European_Union#Economy