pKa component output explanation

Can someone please explain the output of the pKa component when OutputPkaSiteInfo is set to true.

Specifically how and why does the "pKa" value differ from the "base_pka" value and which is the generally preferred value to use?

I've included an example below to facilitate the explanation/discussion

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MoleculeAtom Propertiessmiles
AtomIndexpKaSite_NameBase_pKaSite_FPNum_ClosestExamplesDistance_ClosestExamples
1
2
3
44.78AmineTertiary8.2R1rC;R1rCrC;R1rCrCrN+;R1rCrCrN+rC;R1rCrCrN+C;R1rCrCrN+CC;R1C;R1CC;R1CCO;R1rC\$2;R1rCrC\$2;R1rCrCrN+\$2;R1rCrCrN+rC\$2;R1rCrCrN+C\$2;R1rCrCrN+CC\$210.266666666666667
5
6
77.55AmineTertiary8.2R1rC;R1rCrC;R1rCrCrN;R1rCrCrNC;R1rCrCrNCC;R1rCrCrNrC;R1rC\$2;R1rCrC\$2;R1rCrCrN\$2;R1rCrCrNC\$2;R1rCrCrNCC\$2;R1rCrCrNrC\$2;R1C;R1CC;R1CCS;R1CCS=O;R1CCS=O\$2;R1CCSO-10
8
9
10
11
12
13
14
153Aliphatic_SOOH1.57R2C;R2CC;R2CCrN+;R2CCrN+rC;R2CCrN+rCrC;R2CCrN+rC\$2;R2CCrN+rCrC\$210
OCCN1CCN(CC1)CCS(=O)(=O)O