"She'd hair long's a hoss' tail--an' yaller like gold!" (6) (simile)
Simeon uses this figurative language in recollecting Jenn to Peter. He compares her hair's yellow color to gold, and its length to that of a horse's tail.
"She's like t'night, she's soft 'n' wa'm, her eyes kin wink like a star, her mouth's wa'm, her arms're wa'm, she smells like a wa'm plowed field, she's purty" (15) (simile)
Eben uses this language when lusting after Min.
"I got a notion he's gittin' near--I kin feel him comin' on like yew kin feel malaria chill afore it takes ye" (20) (simile)
Eben says this in Scene 4 of Part I, when anticipating the arrival of his father.
Cabot's blindness (metaphor)
O'Neill uses the metaphor of actual blindness (or in this case, nearsightedness) as a metaphor for Cabot being unable to see what is going on under his nose in terms of Eben and Abbie.
"Hain't the sun strong an' hot? Ye kin feel it burnin' into the earth--Nature--makin' thin's grow--bigger 'n' bigger--burnin' inside ye--makin' ye want t' grow--into somethin' else--till ye're jined with it--an' it's your'n--but it owns ye, too--an' makes ye grow bigger--like a tree--like them elums..." (36) (metaphor)
Abbie speaks in metaphor here, comparing lust and fetal gestation to the nature of the earth.