Well, besides, a freaked out missionary?
Not much, really. I didn't actually break the bowl I dropped when the medium earthquake scared me.
Tokyo averages one earthquake every two months. We were due for one in March; it didn't happen, and then: surprise! There were two last week.
When a small earthquake happens, the house shudders. That's all. It shudders, like me when I'm cold. It shudders, then stops. I am still frozen in place for a good couple minutes afterward, making sure it's over. But it always is. The small one happened late last week as I was getting out of bed. Like I said, it was small, and getting up was only delayed an extra "Earthquake Minute."
The very next day, however, as I was minding my own business, eating my ice cream, the house shuddered again. Again! And this time, it kept shuddering. That's when I dropped the bowl (don't worry, I had just finished eating when the quake started, so no ice cream was harmed in this fiasco) . Usually the quaking/shuddering is finished by the time I get nervous, but this one lasted an extra ... well, an extra minute.
Yes, I know. But earthquakes really bother me!
So, the answer is: the difference between a small earthquake and a medium earthquake is a dropped ice cream bowl.