hopefully KNIME has a solution Welcome to Community!
Objects in KNIME are called nodes and to my knowledge there is no node that can take data from two inputs and perform some custom condition check (except from Python nodes but then you go scripting which is great in case you are fluent in it). In case you are not you can try following. Combine two inputs into one by using Column Appender node or Concatenate node. Then use Rule Engine or Column Expressions node to write your condition(s) and output new column with ok/ko values. Keep in mind that comparison is done row wise so depending on your data and checks you might need some additional manipulations nodes to solve your problem.
From experience sharing data example (dummy works just fine) and desired output results with fast replies, concrete steps and (sometimes) fully functioning workflows that solve your problem
1 - I create a combined String (ex A,B)
2 - I make two join: one takes not matched values => rules engine replace the column’s value with “KO”, the other takes matched values and replaces with “OK”
3 - I concatenate both results for re-having the full data