The 339 is customshop-quality for a Gibson Standard-pricetag. Is has a laminated maple top, where the 336 has a twopiece maple top. The 339 has a 50's-style neck and the 336 a slimmer 60's-style neck.
Found some info:
On the surface, there’s an obvious visual resemblance between the classic Gibson Custom CS-336 and the new ES-339. But while both provide the ideal fusion of solidbody and hollowbody features, that’s where most of the similarities end.
Over 100 years ago, Orville Gibson had a vision to create a guitar with unmatched resonance and an earthy, woody tone. He sought to achieve this by carving the entire body from a single block of mahogany. In fact, it was one of his original goals for making the ultimate guitar, and the CS-336 from Gibson Custom is the fulfillment of that vision.
The new ES-339 (right), also from Gibson Custom, achieves virtually the same mid-range chunky, superior tone as the CS-336, but does so with the perfect union of a laminated maple top, maple centerblock, and spruce contour bracing. This distinct combination makes it a slightly lighter guitar than the CS-336, but allows it to produce a somewhat brighter, fatter, cutting growl. With its classic semi-hollowbody build and styling, the ES-339 is the perfect guitar for players who want the roaring tone of an ES-335 and the playability of a Les Paul.
The neck profiles on the CS-336 and ES-339 also differ. The CS-336 neck contour is Gibson’s traditional slim taper profile, which replicates the shape of necks on the Les Pauls and SGs from the early 1960s, allowing for more comfortable playing styles.
The new ES-339 gives players a choice. The ’59 neck profile is for guitarists who prefer Gibson’s traditional, rounded, chunkier neck, which is most commonly associated with the iconic 1959 Les Paul. In contrast, Gibson’s new slim 30/60 neck has the slim, wide feel of the early 1960s Gibsons, with an extra .030-inches of depth, which makes it a perfect neck profile for today’s faster playing styles.
Gibson’s new Memphis Tone Circuit gives the ES-339 an enhanced electronic wiring circuitry not available on any other guitar. New 500K audio taper pots help to maintain the highs as you turn down the volume. So, no matter where you set the volume control knob, the guitar’s high frequencies continue to cut through any mix, which allows for a superb, open tonal spectrum at any volume.
The CS-336 carries on the vision and ambition of Gibson’s pioneering prophet, Orville Gibson. The ES-339 expands on that vision, and maintains the revolutionary philosophy certain to make it a desirable classic like the models before it.