Actually, the first quote is an example of an apostrophe, for in it Macbeth is speaking to the stars as if they can understand him.
The second quote demonstrates the use of symbolism; the blood that Lady Macbeth says that she will coat the faces of King Duncan's grooms with symbolizes "guilt." Ironically, it will prove to be her own guilt which drives her to commit suicide.
Both quotes also reveal imagery: vivid language that represents objects, actions, ideas.
In particular, the first quote reveals imagery connected to the ideas of "appearance versus reality," "lightness and darkness," and "heavenly bodies." And if you read on, "hand" and "sight" imagery:
Stars, hide your fires,
Let not light see my black and deep desires;
The eye wink at the hand; yet let that be
Which the eye fears, when it is done, to see.
In the first soliloquy, or aside, Macbeth reveals the duality of images: the hiding of stars' "fires" that represent "black and deep desires." It's external (appearance) vs. internal (reality) imagery. As well, the "eye" (knowledge) vs. the "hand" (action). Later, after killing Duncan, Macbeth will not want to go back into the chamber and look on the crime his hand has committed.
The second quote reveals the same "appearance versus reality" duality: hiding or transferring guilt. In this case, it is the external face showing guilt when, in fact, guilt is internal.
In both quotes, the Macbeths will never be able to hide the stars' fires, never be able to wash the blood from their hands, and never be able to hide the guilt from their sleepless nights.
The first of these is an example of personnification. In this figure of speech, an author pretends that an inanimate object or objects (stars, in this case) is able to behave like a human being. In this case, Shakespeare is pretending that the stars can hide their fires as if they were people who could close their blinds.
The second quote, from Lady Macbeth, is an example of alliteration. In this figure of speech an initial consonant sound is repeated. Here, it is a "g." Shakespeare has her say "gild," "grooms," and "guilt."