I worked in one shop where we made pine furniture. Our hardware came in on mahogany pallets, go figger.
We have both types commonly in our forests. Ring porous would be Ash, Oaks, Locusts, Hickories, Walnut, etc. Diffuse porous are the Maples, Poplar, Cherry, Beech, etc, with a less distinct difference in the size of the vessels from earlywood to latewood.
I was first thinking you were asking about tension perpendicular to grain, ripping the board apart widthwise. It sounds like you are asking about horizontal shear, the fibers slipping past each other when the wood is bent. Within the safe working loads orientation doesn't matter, I think there was a small difference in testing to failure.
I think you want to read chapter 4 in the Forest Products Labs "Wood Handbook" if you haven't. Table 4-1 is bending my mind right now, "Elastic Constants of various species"...gee thanks
There are 3 growth rate/density relationships;
1. Ring porous hardwoods. Density tends to increase as the growth rate increases. Hickory and ash tool handles require a low number of rings per inch to be strong, over 30 per inch is a reject ash handle. The vessels are smaller but there are more of them.
2. Softwoods with prominent latewood. Density tends to decrease slightly as the growth rate increases. The correlation is weak and does not exist in some species.
3. Diffuse porouse hardwoods and softwoods without prominent latewood. The density has little direct correlation to growth rate.
If nothing else is known, density rules, use the heavy peg. Whether the pore is in a ring or diffused doesn't matter as much as how much wood is there, wood has weight. Void content of the wood is what determines specific gravity more than anything, well, maybe extractives in that teak. The heavy club is usually the strongest.
Grain orientation does have some strength variables radially vs tangentially. We don't use design values for radial or tangential though, the numbers aren't that different and so they call it "perpendicular to grain" whether a piece is loaded radially or tangentially.
That said, every kid knows how to orient the grain on a bat to avoid shattering it.