Is there any difference in Implementing sigma delta modulator using filters and state space model in FPGA?
Probably not much advantage either way, possibly unless you've got a really high-order modulator (in which case someone else will have to answer!)

If the state-space representation is a single-input single-output system, and if it's linear, and if it's running in steady-state, and if data path widths aren't an issue, then there's no difference between it and a "more traditional" IIR filter implementation such as a set of biquads.

If you've got some super-high-order modulator, or if someone's gone and invented a nifty nonlinear way to get more performance out of a sigma-delta modulator when I wasn't looking, then maybe -- but I doubt it.