World economy and world trade
"Trade", in economics, usually means trade between countries.  So if goods made in, say, the Netherlands are sold in Belgium, that counts as trade.  But if goods made in, say, California are sold in Florida, that doesn't count as trade.  Because the US is a large and populous country, it has a high proportion of internal transactions that count as part of its GDP, a measure of its economy, but do not count as trade.  Many smaller countries, on the other hand, will have a share of world trade exceeding their share of the world economy.