Overall better trained military is a bit of a stretch, but the resource and industry advantage was overwhelming (even if it took time to take hold) but gearing those up is one of the reasons the war took as long as it did. For my money, the earliest the war can end is the summer/fall of 1864, which requires overwhelming victories on land and sea across much of 1863, not the series of 'false battles' across the late summer and fall of 1863 we saw after Gettysburg in the East.
From the historiography perspective, the war ending when it did was probably the best outcome. It went on long enough to grind any further thought of rebellion out of the South, enshrine the end of slavery in the constitution, and put the power of the Federal government firmly supreme over the states.
Say though that the war ends in early 1862/63. If 1862, there is likely no Emancipation Proclamation, which means slavery endures and the South might have cause for further rebellion a few years down the line. If 63, there is no constitutional amendment outlawing slavery, and so the "peculiar institution" effectively continues, but for how much longer? The Emancipation Proclamation can be challenged, especially in places like Missouri, Tennessee and Louisiana, where in many cases slaves will have been prevented from escaping directly by the very Union troops sent to end the rebellion because as historically the EP did not apply to those places under Union control, and if more territory has been taken faster, well...
Like OTL the plantation owners would use their influence, and anger, to not accept it. They will have time and influence to whip up anger, and potentially another rebellion as more people oppose outright Emancipation and Abolition without a war to make it seem necessary. Slavery may well take longer to die out.