Just to show that water inside eliquids is very important for the behaviour in temperature. So, eliquid with different water percentage has different evaporation temperature.
When we compare VG eliquid with PG eliquid for the behaviour in temperature they get evaporated, we have to take note for the water concentration inside. All the VG or PG eliquids do not have the same concentration of water and/or flavour inside. If a PG eliquid does not have water at all (only flavour e.g.5% inside) then it is very different to another eliquid of VG having 10-15% water and 5% flavour dissolved.
If you take a close look in boiling points' differentation you will see that 5% difference in concentration give even 30 degrees difference in boiling point (VG 90% or 95% concentrated).
Just to be more accurate and realistic.

