Internal Ballast its inside the bulb itself so you can't see,
External Ballast is like a square metal box with wires connected to the bulb holder.

DownLight is the current Trend.
As with all trend it will pass.

Usually when you go to any light shop for D/L, the 1st D/L they offer is YET Plus from China. (including Wong Lightning), so the no brand is actually YET Plus.

Then there is Evenzzo (YET sister brand, same wan)

Then YLI if you ask really hard. Malaysia Brand, Ipoh mali. Pricier

In Wong Lighting , their in-house brand is Eliminuz (weikee's D/L), I think its Taiwan Made.

I heard in Hong Kong, the trend now is LED wall lighting or something like that. Dunno true or not. Downlight is the obsolete trend in HK. Anyone knows of this??