Flatlock seams are extremely strong and durable and will last the test of time. The stitching penetrates the entire way through the rubber thickness, making a flat and robust seam. This full penetration seam can allow some water to enter through the seams. Most suited for spring suits / vests / long janes etc.
Triple glued and Double blind stitched seams produce a much stretchier and warmer seal by glueing the rubber sheets together then stitching them through only half the thickness of the rubber. This allows a much stretchier seam and significantly reduces water entry making a much warmer wetsuit for cooler climates. An additional liquid seal is sometimes added on top of this GBS seam to to create a completely water tight seal. GBS seams are more suited for winter wetsuits and colder climates. Liquid seals are generally added for those extra frosty climates. Tape is usually used on internal connection points and other areas of increased movement to provide extra strength and warmth to those areas.