Latin [w] is labiovelar, just like [gʷ]; no palatal in this case. The difference is mostly order of operations:

• Latin - lenition, then loss of the velar articulation: [gʷ]→[w]→[β]
• Greek - loss of the velar articulation, then lenition: [gʷ]→[b]→[β]

then [β] evolving into [v] in both.