http://www.stormcam.org/altimeter-compass/
Is there a difference between a digital watch with compass, altimeter, barometer, thermometer, weather station
a watch GPS or is it basically the same?
A GPS Watch uses satellites to determine the exact location (latitude and longitude), and uses also the satellites to determine altitude (some in use have a GPS altimeter, but most use the GPS signal to calculate altitude) A digital compass even tell you what direction you go (in fact, whose direction is north, south, east, west). You do not know where you (unlike GPS). The barometer and thermometer does not use GPS satellites, and if a GPS unit has these characteristics because they have built instruments Segregated in the unit.
Review of Casio Protrek Triple Sensor Altimeter Compass Pro Trek Solar Watch PRG-110T-7V