Pungent, piquant, poignant, racy, spicy, snappy are comparable when they mean characterized by sharpness, zest, and a piercing or gripping quality.
Pungent applies especially to a sharp, piercing, stinging, biting, or penetrating quality, primarily of odors; it may suggest power to excite or stimulate keen interest or telling force and cogency.
Piquant may indicate an interesting or appetizing tartness sharpness, or pungency that stimulates or a zestful, arch, provocative, challenging, or exciting quality that is individual or peculiar.
Poignant (see also MOVING ) may describe what is sharply or piercingly effective upon the senses or stirring to one’s inmost consciousness or deepest emotions.
Racy may suggest verve, dash, tang, or vitality manifested with lively free heartiness. Sometimes the term may carry the additional hint of passing beyond the bounds of propriety or good taste.
Spicy describes what is seasoned or made redolent of spice; in extended uses it may suggest the piquant, smart, spirited, sensational, or scandalous.
Snappy suggests briskness, animation, dash, wit, or risqué quality.