This leash can be a little longer (up to 8 feet) and also a nylon leash like the walking leash. This one will be worn by your puppy for the first six months or so of their life constantly in the house. You will want to remove the loop at the end of the leash to prevent your puppy from getting caught on something in the house. This leash will alow you to quickly remove your puppy from a situation where they are doing something "naughty" like chewing, scratching, etc. without making it a game of chase. I will link an article about house lines and how to use them.
An inclusive checklist for bringing home a new puppy (straight from the mouth of a dog bather, vet tech student, and dog lover all in one). I linked many informational articles as to why you need these things, and what considerations you should make when choosing your new puppy supplies.