Which method is easier to make a baby's blanket knitting or crochetting?

Neither is easier or harder. Some folks have an easier time learning to knit and some to crochet. It also depends on the pattern you tackle. Some patterns are very easy, using simple stitches. Other patterns are more difficult. Some designs might be easier in crochet, some in knitting. It is, for example, easier to do cables in knitting than in crochet though it is possible to do them in both crafts.