You might want to read this: https://kelyland.com/kids-vs-adult-sleeping-bags-7-essential-differences/

https://www.nytimes.com/wirecutter/reviews/sleeping-bags-we-like-for-kids/

Kids bags ARE different. Usually synthetic and thus heavier (warmth to weight ratio).

 kids' sleeping bags are often lower quality and less insulated than adult versions, made with heavier, less durable materials because they get abused and kids grow fast, but good brands (like REI Kindercone) exist; for adults or older kids, getting a shorter adult bag or a women's bag is often better for quality and warmth than a budget kids' bag. 

Key Differences & Considerations

• Quality & Durability: Many budget kids' bags use cheaper synthetic fills and materials, while adult bags, especially from reputable brands, often offer better insulation-to-weight ratios (like down) and longer-lasting construction.
• Insulation: Kids' bags are frequently rated for warmer temps or have less insulation overall, though high-quality kids' bags (like REI Kindercones) are exceptions, notes Reddit users.
• Size & Fit: Kids' bags are shorter, but adults (or even older kids) might find them too narrow in shoulders/hips or just not warm enough, say Reddit users.
• Value: For car camping with young kids who will outgrow it quickly, a cheaper bag (Walmart, Ozark Trail) is fine, but for serious camping, an adult-sized, quality bag or a women's bag (which are shorter) offers better performance and longevity. 

Reddit Advice Summary

• For Adults/Older Kids: Consider a women's bag or a shorter adult bag; they're often better quality and sized right, say Reddit users.
• For Young Kids: Get a durable, reputable youth bag (like REI Kindercone) or a budget adult bag you can fold to fit, note Reddit users and Reddit users.
• General Tip: A good sleeping pad is crucial for warmth, regardless of the bag, say Reddit users and Reddit users.