Sensor for Weight Measurement
The main mechanical differences between an expensive 20 kgf load cell and a cheap one will be -

Repeatability
Drift
Hysteresis
Linearity

Repeatability
You load it with 10 kg, take it off, load it again. How well do the readings agree?
Drift
You load it 10 kg, and leave it on there. Read it now, read it in an hour, read it in a month. How well do the readings agree?
Hysteresis
You load it with 10 kg. Read it. Add another 5 kg. Now remove the 5 kg. Read it again. Does the increasing load reading match the decreasing load reading?
Linearity
You load it with 5 kg. Add another 5 kg. Is the second reading twice that of the first?
With a cheap one, you may get many 10s of grams error at any one of these steps. With an expensive one, you may get sufficient mechanical goodness to be able to use the reading range of a 20 bit ADC to give you 20 kg full scale with an accuracy of a gram.