predict - делает прогноз значений на основе поданной модели:
predict(lm(y ~ x))
summary is a generic function used to produce result summaries of the results of various model fitting functions. The function invokes particular methods which depend on the class of the first argument.
summary(c(1,2,3))
# Min. 1st Qu. Median Mean 3rd Qu. Max.
# 1.0 1.5 2.0 2.0 2.5 3.0