The Intrepid-class starship that was launched in the latter half of the 24th century by the Federation was no match for the much more capable Sovereign class or even the Defiant-class starship of its time period.
The intrepid class featured several recent technological innovations that had recently become available, including bio-neural circuitry, advanced sensors, variable geometry warp nacelles, and the Emergency Medical Holographic program (everyone’s favorite doctor).
But the modified version of Voyager was something entirely different. Modified by future Kathryn Janeway from the year 2404, Voyager was provided with some very advanced tech indeed; advanced weapons (transphasic torpedoes) and ablative generators that proved highly resistant to Borg weaponry.
“Captain’s personal log, stardate 54973.4. We’ve begun outfitting Voyager with Admiral Janeway’s upgrades. As soon as the major modifications are complete we’ll reverse course and head back to the nebula. Though I’ve had some strange experiences in my career, nothing quite compares to the sight of my future self-briefing my officers on technology that hasn’t been invented yet.”