A study of the phase structure of two linear polyethylene fractions has been carried out by Raman spectroscopy and from the analysis of the interface distribution function from the SAXS intensity data. Very good agreement is obtained for the core crystallite thickness, the liquid-like region, and the thickness of the interface from these two independent techniques. Moreover, the X-ray analysis distinguishes isothermally formed crystals from quenched crystals in cases where the Raman technique is not selective.