The TG 1st and business lounges are in the same room, separated only by a divider and monitored by lounge personnel. Because of that, the TG lounge can be a bit noisier.
Food is ok in both lounges; the UA place had some decent dim sum and the TG lounge an ok assortment of Cantonese and Thai items.
The best part of the TG lounge for me, by far, is the massage chair. Incredibly fun and relaxing.