Verizon Wireless and straight talk are NOT the same carriers and are unrelated.
They both use CDMA, which means the network will be very similar but the call quality will not be. Verizon Wireless is the major provider of the towers that straight talk uses (as straight talk through tracfone doesn't own any towers) which means Verizon Wireless will value their own customers over another carriers customers. This means your calls are more likely to get dropped over a Verizon Wireless customer and you may lose coverage from time to time. Also, the possibility of your coverage area getting bigger and better is slim to none.