[Ghazban]

I don't know what TAG is in NL; when I read it as a read on an opponent, I pretty much ignore it and hope the poster has given me more specific information.

LAG is better-defined. A LAG is loose and aggressive (duh). Loose and aggressive can win money in NL but its pretty high variance. Good LAGs are excellent postflop and know when to apply pressure to make their opponents fold and when to back off or conded the pot. They normally excel at hand reading and have no fear whatsoever.

Most LAGs at mid- and low-stakes are bad LAGs. They push too hard with too many marginal hands against the wrong players. They try to push calling stations off of top pair when they have nothing but a gutshot. They push hard too often and, as a result, don't have the folding equity they need for their plays to be +EV.

Loose and tight are both winning styles if played properly. Good LAGs (like Mahatma/Spirt Rock) are lionized for their play because its sexy and exciting to watch/play. Tight play can be equally profitable but its far less interesting to watch and discuss.