AVERAGE in SQL query is giving different result from AVERAGEX in DAX

I have the following SQL query :

SELECT
AVG(
nvl("PROP_TxMarge",0) * ((nvl("PROP_MtDemandeFin",0) - ( nvl("ENV_MontantInitial",0) - nvl("ENV_MontantDisponible",0) ) ) * nvl("POOLFIN_Pct",0))
)
FROM myTable

and this is the KPI syntax I am using :

KPIFormula := AVERAGEX('myTable',

 

[PROP_TxMarge] *

(

( [PROP_MtDemandeFin]

- ( [ENV_MontantInitial]

- [ENV_MontantDisponible] ))

* [POOLFIN_Pct]

)

)

I am having different results.