Yes, it can use interpolation, see here.
As default, the solution gets evaluated over all the timepoints using the underlying function of the differential equation system.
Your first case produces an DiscreteDataDrivenProblem, given that you do not use ContinuousDataDrivenProblem as a constructor. Given that you are trying to learn a ODE, you would need to provide the derivatives, e.g. by using DX = Array(sol.(sol.t, Val{1})) . The constructor using the solution is able to infer that you are using a continuous solution here and will handle this.