The floss silk tree is native to South America. It is sometimes called kapok, but that name more correctly refers to Ceiba pentandra. Like kapok, the fibre from the fruit of Ceiba speciosa is also sometimes used for packing materials, but the fibres are short and not suitable for weaving.
The Buenos Aires street tree in the second image shows the strange spikes on the trunk. These are poorly understood, but according to the Wikipedia article they hold water for dry periods. Young trees have chlorophyll in the bark, giving the tree the ability to photosynthesize when leaves are absent. The trunk has a bottle shape and often leans. I have not found the reference, but would guess that this is the origin of the Spanish common name, palo borracho (drunken tree).
Ceiba speciosa puts forth quite a show when it blooms and is used as an ornamental tree in warm climates. The University of Florida Extension has a good fact sheet about the tree (and shows the flowers, which were not present during my visit in Argentina.) Be sure to check out the flower and fruit pictures at the bottom of the page.