Market cap is a token's price multiplied by its circulating supply, meaning the tokens that can currently be traded. Fully diluted valuation (FDV) is the price multiplied by the total supply, including tokens that are locked, vesting or not yet released.
Which one matters for memecoins
Most memecoins launch with the whole supply circulating, so market cap and FDV are the same. The difference matters for tokens with locked team or treasury allocations. Those tokens can be released later and add selling pressure.
The bigger trap is market cap without liquidity
Market cap is calculated from the last traded price. It doesn't tell you how much money could actually flow out. A token "worth" $5M with $50K of liquidity can't absorb much selling. Always check liquidity next to market cap, and check how much of the supply sits with a few holders (holder concentration).
Educational content only. Not financial advice.