Understanding Dono Mein Kya Fark Hai: Difference between Joint Hindu Family and Hindu Undivided Family

I'm having a brain wave block on this one and I'm hoping someone can help me out here. Can someone please explain the difference between Joint Hindu Family and Hindu Undivided Family in the context of Company Law? I keep getting these two concepts mixed up and it's causing a massive confusional mess in my head. What is the exact distinction between the two? Are they synonyms or is there a significant difference? Please help a student out here and provide some clarity on this confusing concept.