Mercadillo vs. mercado de pulgas vs. rastrillo vs. tianguis
Each of these terms refer to types of markets commonly found in Spanish-speaking countries. They all generally translate to 'flea market' but come with slight regional or cultural nuances.
Mercadillo
A 'mercadillo' is a type of open-air market that commonly takes place in Spain. The term is used broadly and can encompass various types of temporary markets, including flea markets, farmer's markets, and arts and crafts fairs.
El mercadillo de la Plaza Nueva se celebra todos los sábados.
(The flea market at Plaza Nueva takes place every Saturday.)
Mercado de pulgas
'Mercado de pulgas' directly translates to 'flea market'. This term is used widely across all Spanish-speaking countries, and describes a type of secondhand goods market typically arranged in stalls.
Fuimos al mercado de pulgas para buscar muebles vintage.
(We went to the flea market to look for vintage furniture.)
Rastrillo
'Rastrillo' is another term used in Spain to indicate an open-air market where second-hand items are sold. It's often used interchangeably with 'mercadillo'. However, it can also refer to a type of yard or garage sale.
Este fin de semana hay un rastrillo en el barrio.
(There's a yard sale in the neighborhood this weekend.)
Tianguis
'Tianguis' is a term used primarily in Mexico. While it can describe all sorts of street markets, it's also used more specifically to mean a market where second-hand goods are sold.
Cada domingo se organiza un tianguis en la plaza del pueblo.
(Every Sunday a flea market is organized in the town square.)
Summary
While 'mercadillo', 'mercado de pulgas', 'rastrillo', and 'tianguis' all refer to similar types of markets, the usage varies based on region and sometimes by the specific nature of the goods being sold.