Porosity is mainly a function of dicot woods. This term refers to how the vessels are distributed. Grain refers to the alignment of the xylem cells. The presence of knots or burls may also be involved. The figure also differs greatly depending on how the wood is cut.
Density is the weight per unit size.
Compared to water, woods that have a density greater than one will sink. Lignum vitae has a density of 1.23. Balsa has a density of 0.13. Pine has a density of 0.35-0.50. Oak is about 0.60.