What is the primary difference between 'Stemming' and 'Lemmatization'?

1. ক
   Stemming uses a dictionary, Lemmatization uses heuristics
   
2. খ
   Stemming chops off word endings, Lemmatization uses morphological analysis
   
3. গ
   They are identical processes
   
4. ঘ
   Lemmatization is faster but less accurate