Intermediate patterns assume you're comfortable with the basic stitches and ready to add increases, decreases, and working in continuous rounds. Most also introduce one or two of: simple cables, basic lace repeats, or colour changes.
Gauge starts to matter here — particularly for fitted items like hats and sweaters. Every pattern includes a gauge swatch target and an estimated finished size. If your swatch comes out smaller than the pattern's gauge, go up a hook size; if larger, go down.