Question

is there a difference between weight in air and weigh Mt in water during floatation

Answer 1

Yes there is a difference.
In air the object is in a free fall, hence the weight is according to gravity.
but in Water a Buoyant force opposes, which causes floatation of light objects
thus, weight in air > wieght during floatation

Answer 2

yes.

mass of the body be m.
density of the body be d.
let V be the volume of the body  which is inside water.
d_w = density of water

weight of body in air:  m g

buoyancy force on th body when floating on water =  V d_w g
since it is floating on water,    m g = V d_w g

Since the forces of buoyancy and the weight of the body due to gravitation being equal, the body floats on water and is in equilibrium.

Apparent weight of the body = m g - buoyancy force = 0

the difference between weight in air  and  apparent weight in water  =  m g