The Marker
class has a Position
property, so
double latitudeDifferenceInDegrees = marker1.getPosition().latitude - marker2.getPosition().latitude;
double longitudeDifferenceInDegrees = marker1.getPosition().longitude - marker2.getPosition().longitude;
You can convert the latitude difference into a distance in meters - each degree is equal to 110.574 kilometers:
double latitudeDifferenceInMeters = latitudeDifferenceInDegrees * 110574;
You can't do the same for longitude. On the equator, a longitude degree is about 111 km, but near the poles, it is much less. If you are only using this for short distances, I'd go for
double longitudeDifferenceInMeters = longitudeDifferenceInDegrees * 111320 * Math.cos((marker1.getPosition().latitude + marker2.getPosition().latitude) / 2);
Note that both can give negative values if the first marker lies south or west of the second marker. If you're interested in positive values only, apply Math.abs()
.