arXiv:2605.28106v2 Announce Type: replace-cross Abstract: We investigate the connection between Gaussian processes and Gaussian random elements in reproducing kernel Banach spaces. We show that the covariance operator of a weak second-order Radon probability measure on such a space is uniquely determined by a symmetric positive-definite function. In the Gaussian case, we characterize those functions that arise from covariance operators in terms of $\gamma$-radonifying operators. Building on these results, we extend Driscoll's theorem to the reproducing kernel Banach space setting.