Join Query-capture Excluded Data

I have 2 tables, table one with 772 pieces of compliant data. Table 2 has 435 pieces of data that meet another criteria (all the columns are identical it was just passes through an additional filter). I need to capture the values that are excluded from table 2.

Example Table 1
ID some value
1 x
2 x
3 x
4 x
5 x

Table 2
ID some value
2 x
3 x
5 x

I need to capture the data from ID 1 and 4 and assign a new value to it, it is extra compliant data. Thanks!