SAP MM

due to yearly banal study to supplier X000000XX, we person recovered that quantity reported via EDI inventory study is antithetic from quantity shown successful our SAP (transaction MB5B). The acrophobic day is 31.12.2024. Material X000000XX(X000000XX). Quantity reported via EDI is 14 682 pcs and SAP shows 13 842 pcs. Both lone study connected Consignment stock, thing else. Plant xxxx.
Quantity successful IDOC connected 31st dec is 14682.
And MB5B study with aforesaid day ha quantity 13842.
So quality of 840 quanity successful IDOC and MB5B.

Why this is happening?
Which quantity should beryllium correct?