An under scarf can be defined as a small piece of fabric used by hijabis to cover their head. It is usually worn under a scarf or hijab. It comes in many different shapes, colors and designs and is useful for to keep slippery and sheer hijabs in place.
Bonnet cap is made of a jersey type cotton fabric and is also non slippery. It is placed over the head and fastened at the back using the ties attached at the end. It has a small opening at the back once tied, so you can let the hair through.
Tube underscraf probably rivals the tie back bonnet cap in terms of comfort-ability due to its opening from both ends. It is made either of stretch cotton or polyester and is non slip.
Sizes: Tube under scarf is ready made and is a one size fits all due to it’s stretch where as the tie back bonnet cap is suitable for all head sizes as it can adjusted to your fit.
Support: A tube under scarf due to its opening on both sides holds your hair easily, however a bonnet cap because of its ties attached at the end does not provide any support making it uncomfortable for hijabis with heavy hair. In addition, the ties usually end up tangling hair and causing irritation.
Comfort: A bonnet cap can be adjusted to the hijabi’s preferences and could be tied to either cover or uncover their ears on the other hand tube underscarf is made in such a manner which covers ear.
Flexibility: A tube underscarf ensures low or no headaches based on its flexible and stretchy material while a bonnet cap could cause head aches if tied to tight.
Final Verdict: According to my preferences I love wearing tube underscarfs due to its better support function for my hair. Some people may defend saying that it may be lose at times, what I tend to do to have a tighter fit is use a no-snag hijab pin.