Every Vtube---whether it's called a Lavatube or some other vendor re-branded name---is made by one of two Chinese manufacturers: either L-Rider or Young-June.
L-Rider currently has two versions: the "original" Lavatube v1 in the basic Vtube body, with plastic-covered metal end caps and various color paint finishes, and the v2 "Lambo" in chrome or stainless (only one production run made Lambos in stainless steel) with all metal caps and an eGo-style 510 top connector with a spring-loaded "floating" positive pin. Both versions share identical inner electronics and a 2.5 amp limit that provides no more than 3.8 volts to power a 1.5 ohm dual coil carto. All L-Rider tubes have a red power button and use constant voltage (flat DC) from the boost regulator.
Young-June currently has
three versions: v1.5 and v1.5t with metal end caps in black or silver paint finishes, a flush 510 top connector, atty/carto resistance checking, and a 3.2 amp limit. The new v2.0 adds a triple-plated chrome finish over brass, an eGo-style 510 top connector, and a similar amp limit (testing has not confirmed the claimed 4.0 amps). At 3.2 amps, 4.6 volts is the max voltage available to power a 1.5 ohm dual coil carto. All Young-June Vtubes have a power button that matches the body color and use PWM (pulse-width-modulation), also called "switching," to deliver voltage from the boost chip.
Phil Busardo's review compared the L-Rider v2 chrome "Lambo" with the Young-June chrome v2.0.