QUICK ANSWER
"Tarde" is a form of "tarde", an adverb which is often translated as "late". "TA" is an abbreviation which is often translated as "TA". Learn more about the difference between "tarde" and "TA" below.
tarde, la tarde(
tahr
-
deh
)An adverb is a word that describes a verb, an adjective, or other adverbs (e.g., to run quickly, very tired).
A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).
a. afternoon (from noon until sunset)
Esta tarde me voy de compras con mis amigas.I'm going shopping with my friends this afternoon.
b. evening (around sunset)
Te veré esta tarde después del trabajo.I'll see you this evening after work.
TA(
teh
-
ah
)An abbreviation is the shortened form of a word or group of words (e.g., "UFO" = "unidentified flying object"; "p." = "page").
a. TA
Los términos médicos de este libro fueron tomados de las categorías de la TA.The medical terms in this book were taken from the categories of the TA.