A PRL, or Preferred Roaming List, applies to every network technology and can and does improve connectivity in some cases. That includes 2G/3G/4G technology
What a PRL does is give your phone a hard copy list of towers owned by Verizon and ones used by roaming partners so that no matter what state the phone is in, it can easily locate and authenticate on the closest tower. It also determines the priority by which your phone searches for a specific tower when used in conjunction with the home cell site identifier, or SID.
The PRLs work in tiers: Alltel CDMA, Verizon CDMA, Verizon/Alltel Hybrid CDMA, and Verizon CDMA/LTE. The tiers are designated by the first two digits of the PRL. In the LTE phones the tier is 15xxx now, but was 14xxx when it was first released.
In theory, all phones of the same tier *should* be the same PRL, but I noticed this is not the case. This also does not appear to be affected by the plan you have either. I only notice a somewhat common trend depending on the billing region you are in that I notice (NE, S, MW, W), but even that is no guarantee.