Human: What are the differences between a t-shirt and a polo shirt? Assistant: 
A t-shirt is typically made of cotton or other breathable material, while a polo shirt is usually made from a blend of polyester and cotton. T-shirts tend to be more casual in nature, with an open neckline and short sleeves, while polos are generally more formal, featuring a collar and longer sleeves. Polo shirts also typically have a higher neckline than t-shirts.