As Ken Streiff says, the stength is more in the joints than the timber itself - the amount of timber you have in a bed to make it look good is far more than required to support all the weight. However, I would say that the engineered wood (or even John Williams suggestion of Modified Wood) would be more stable over time. read more
Engineered wood is commonly used to replace structural softwood beams and is stonger than softwood. Teak, on the other hand, is a hardwood and is likely even stronger than engineered wood of the same dimension. The key thing is that neither is a common choice for a bed. Teak is expensive and will ruin your tools in no time due to its silica content. read more
Teak wood is another type of hardwood. It has a smooth grain and texture. It has a yellowish brown hue, which may mature overtime to a silvery-grey finish. read more