Difference between Joiner and Union Transformation

• Joiner Transformation can join only two input groups whereas Union Transformation can join multiple input groups
• Joiner Transformation combines the records horizontally based on the join condition whereas Union Transformation joins the records vertically
• Joiner Transformation supports Normal join, Master outer join, Detail outer join and Full outer join whereas Union Transformation does UNION ALL
• Joiner Transformation removes duplicates whereas Union Transformation doesn't   

Both these transformation supports heterogeneous joins(Join between two different data sources Ex: Oracle + SQLServer)