Depends on where you are going to use them. For deck hangers and such I would suggest nails are they have higher shear strength. However, for deck boards I would use screws.
The shear value will vary depending on what species of wood it is being fastened to, what gauge of steel it is going through, etc. Please refer to the National Design Specification (NDS) Table 12P which has allowable shear loads for nails with steel side members ranging from 20 to 12 gauge thickness. SCN nails are ASTM F1667 compliant, so they can be calculated per the equations in NDS (or customers can use the NDS tables). The complete NDS (and all the fastener tables) is available for free on the American Wood Council’s website: (Link to 2018 NDS) https://www.awc.org/pdf/codes-standards/publications/nds/AWC-NDS2018-ViewOnly-171117.pdf. Thank you!
Nails and screws are technically termed "fasteners." In other words, nails are fasteners...