With 3d prints this is usually framed as layer adhesion. Within one layer (so in the x-y plane) you are basically "along the grain" since the strands form loops and other 2d shapes within the layer. Between layers (== in z direction) you only have the adhesion between different strands holding the layers together, which is equivalent to going across the grain in wood.

CNC kitchen on youtube does a lot of strength and impact testing, e.g. [1] (results at 9:55). "Across the grain" you have half the strength in PLA (and similar numbers in all filament types except TPU). Or if you prefer manufacturer numbers, [2] is the datasheet for a random PLA filament. It also shows worse numbers in every metric in the Z direction (across the grain).

The difference isn't as severe as in wood, but it's big enough that it is something you have to consider in structural parts

[1] https://youtu.be/dOzVuoBP9gY?t=535

[2] https://polymaker.com/wp-content/uploads/lana-downloads/Poly...