Differences in glucometers measurements

Hello good!
I have two glymeter of two different brands: one that I bought by eBay (Codefree SD) that helped me the first days and a freestyle lite that gave me in the SS.The latter is the one I use since then.
Today to try, I have measured the glucose with the two, and with the same puncture and there were almost 20 points of difference (82/111).
I have hallucinated!Is this difference between some teams and others normal?
What teams do you recommend?

That really is no difference when you are boring to check.
Even if you repeat the analytics with the same glucometer, you will see much greater differences.
The glucometers are not exact science or repeating in it because I do not even tell you if you check with another.
Many hypoglycemia and hyperglycemia that we do not know why they happen are problem of erroneous results that mark glucometers in glycemia.
Normally the differences between two glucometers are usually the same depending on the stretch where blood glucose is found, but I repeat that if you repeated in the same glucometer for a while you would take many surprises, the problem is that they do not give strips to be able to do this.