Q:

Compare two files and output any lines that are different

I get a report daily and it has around 8500 lines on it, I have been trying to make a macro that will do what I have been doing manually.  The problem with the report is that all the lines are not the same format(i.e Line 1: number,text,text,number and Line 2: text, number, number, text). 
I want to compare the new file to the old file and output the new differences.  I can get the macro to run through the 2 files but it isn't flagging any of the lines as different but I know they are. 
Sub test()

Dim yesterdayFile As String
Dim todayFile As String

yesterdayFile = Application. GetOpenFilename()
todayFile = Application. GetOpenFilename()
Dim yesterdayLine As String
Dim todayLine As String
Dim txt As String
Dim i, j, k, sameLine As Integer
Dim wkbTemp As Workbook
i = 1
j = 1
k = 1
sameLine = 0

Open yesterdayFile For Input As #1
Do Until EOF(1)
    sameLine = 1 'reset write operator
    Open todayFile For Input As #2
Line Input #1, yesterdayLine
    Do Until EOF(2)
        Line Input #2, todayLine
        If StrComp(yesterdayLine, todayLine) = 0 Then 'compare lines in files if same then flag write operator to 1
           sameLine = 1
        End If
        j = j + 1 'inner loop counter
    Loop
If sameLine = 0 Then 'if write operator is not active then output line
    Cells(i, 1) = yesterdayLine
    i = i + 1 'counter for cells
End If
Close #2
k = k + 1 'outer loop counter
Loop

'test line to see if its eof
Cells(1, 10) = i
Cells(2, 10) = j
Cells(3, 10) = k

Close #1

End Sub

Test files being used to run the test faster:
Yesterday File:
10001,April,Apple
10002,Book,Bush
10004,Dog,Days
10006,Free,Food
10008,Happy,Help
10009,Ikky,Icing
10010,Jamming,Jupiter

Today File:
10001,April,Apple
10002,Book,Bush
10003,Cat,Cattle
10004,Dog,Days
10005,Echo,Eggg
10006,Free,Food
10007,Good,Game
10008,Happy,Help
10009,Ikky,Icing
10010,Jamming,Jupiter

Note: In the real data there is no "unique ID field"
Counters end with correct numbers so I know its running through the recursions
EDIT: I know this can be done easily with other languages, but I can only access excel vba from my work terminal and can't take files off network. 

A:

So after Much trial and error I answered my own question, Thank you for all the responses but going from 72mil iterations to 3bil just wasn't an option. 
What my code ended up looking like
Sub test()
'Freeze window
Application. ScreenUpdating = False
Application. Calculation = xlCalculationManual

'open files to edit
Dim fileA, fileB As String
fileA= Application. GetOpenFilename()
fileB = Application. GetOpenFilename()

'setting variables
Dim lineA, lineB, DQ As String 'read in lines and double quote     variables
Dim i, sameLine As Integer 'row counter and testing(could have used boolean?) 
Dim newLine 'object creation for array of line
i = 1
DQ = Chr(34) 'character 34 is "

Open fileA For Input As #1 'open file 1 for append
Do Until EOF(1) 'Outter loop to run through file 1
    sameLine = 0 'reset write operator
    Open fileB For Input As #2 'open file 2 for append
    Line Input #1, lineA'read in line from file 1
    Do Until EOF(2) 'inner loop to run through file 2
        Line Input #2, lineB 'read in line from file 2
        If StrComp(lineA, lineB) = 0 Then 'compare lines in files if same then flag write operator to 1
            sameLine = 1
        End If
    Loop
    If sameLine = 0 Then 'if write operator is not active then output line
        count = Len(lineA) - Len(Replace(lineA, "|", ""))     'count number of columns needed for output
        lineA= Replace(lineA, DQ, "") 'removing all double     quotes from line
        newLine = Split(lineA, "|") 'spliting line into object with | as delimiter
        For counter = 1 To count 'placing line in row
            Cells(i, counter) = newLine(counter - 1)
        Next counter
        i = i + 1 'counter for cells
    End If
Close #2
Loop
Close #1
'unfreezing window
Application. Calculation = xlCalculationAutomatic
Application. ScreenUpdating = True
End Sub

This works on .txt and .csv and compares the input lines directly BEFORE writing them to any cells.  My problem was unique because of time stamps at the end of each line which I added a few lines to fix.