In Rio and Sao Paulo, this is a fledgling Samba School - smaller than a Samba School and often without elements such as the Comissão de Frente.

a moving, cordoned off section on the street with a float and thousands of people and live music

A group of people who parade together in samba costumes to samba music. They can include instrument or not. They are many times the progenitors of samba schools and can be quite large in size. Normally, the block follows a costume theme.

a carnavalesque band, and Carmelitas was formed sixteen years ago by a group of friends who would get together to play near the Parque das Ruinas in Santa Teresa

a roped off area around each truck which you are only allowed to enter if you bought the right T-shirt