Beyond building differences what is important to understand is that the way of measuring earthquakes is a logarithmic scale. The difference between 6.8 and 7.5 is significant, logarithmically.

Also Richter isn't used anymore, really, moment magnitude is the scale typically used https://www.usgs.gov/faqs/moment-magnitude-richter-scale-what-are-different-magnitude-scales-and-why-are-there-so-many