The Brazilian festival is known for its over the top outfits and the African and Brazilian music associated with the festival. The festival is not only cultural but also religious as well. The carnival is an annual festival held during the Friday to the Tuesday before Ash Wednesday, marking the beginning of Lent (the forty day period before Easter). The festival consists of a set of styles that define the samba genre (both solo and partner dances).
The Samba no pé is one of the solo dances that is most often danced impromptu when samba music is played.The rhythm is 2/4, with 3 steps per measure. The basic movement is the same to either side, where one foot moves to the outside lifting up just before the first beat .
This is the type of Samba one sees in the Brazilian Carnival parades and in other Samba carnivals over the world. This is also one of the most popular sambas.
Samba Axé is another type of solo dance that is performed in the carnival. The dance is completely choreographed and the movements tend to mimic the lyrics. It's a very energetic kind of dance that mixes elements of Samba no pé and aerobics.
The ballroom samba is quite advanced and needs time and some experience to perfect. As a result, it is often learnt by people who have been dancing for quite a bit of time.
I have attached videos of the festival and the ballroom Samba to showcase the difference in the styles performed.