Function comparison

There has been something that I haven't quite been able to get my head around...

I noticed that there are 2 ways I can call a function.

Method 1: I could call this function with fillList();.

function fillList(%this){
	%this.clear();
	if (%this == UnitList)
		%filename = "fps/server/scripts/armies/armyData.cs";
	if (%this == ObjectLabList)
		%filename = "fps/server/scripts/armies/objectData.cs";

	%LineCount = ReadListFile(%filename);
	for ( %i = 0; %i < %LineCount; %i++ ){
		%RowInfo = buildLineDataString($DataSheet[%i]);
		%this.addRow( %i, %RowInfo, %i );
		echo(%rowInfo);
		echo("Unit This = " @ %this);
	}	
}

Method 2: I could make two functions and call them with UnitList.fillList(); and ObjectLabList.fillList();.

function UnitsList::fillList( %this ){
	%this.clear();
	%filename = "fps/server/scripts/armies/armyData.cs";
	%LineCount = ReadListFile(%filename);
	for ( %i = 0; %i < %LineCount; %i++ ){
		%RowInfo = buildLineDataString($DataSheet[%i]);
		%this.addRow( %i, %RowInfo, %i );
		echo(%rowInfo);
		echo("Unit This = " @ %this);
	}
}
//-------------------------------------------------------------------------------------------------------------------------------------------------------------

function ObjectLabList::fillList( %this ){
	%this.clear();
	%filename = "fps/server/scripts/armies/objectData.cs";
	%LineCount = ReadListFile(%filename);
	for ( %i = 0; %i < %LineCount; %i++ ){
		%RowInfo = buildLineDataString($DataSheet[%i]);
		%this.addRow( %i, %RowInfo, %i );
		echo(%rowInfo);
	}
}

My question is, what is the advantage of calling functions with Method 2?

I know this is a pretty basic question, but after reading through the docs and tuts, I can't figure this out. I know how to create them, I am not sure why I would. Please help me in my understanding of this.

Thanks guys!
-Jeff