title: display unique values between two dataframe columns - pyspark
body: <p>say I have two "ID" columns in 2 dataframes, I want to display ID from DF1 that doesnt exists in DF2</p>
  
  <p>I dont know if I should use join, merge, or isin.</p>
  
  <pre><code>cond = [df.name != df3.name]
  df.join(df3, cond, 'outer').select(df.name, df3.age).collect()
  </code></pre>
  
  <p>not sure if changing the condition will give me the result. </p>