Neither of those statements is true. Russia is suffering less casualties than Ukraine because they have an enormous firepower advantage. And the most heavily fortified and urbanized part of Ukraine is the Donbass. It actually has been getting easier for Russia the more it has broken through those lines that have been fortified since 2014, and the more it has attrited and degraded the army that NATO had trained and equipped in Ukraine, leaving Kiev having to increasingly resort to dragging unwilling and unfit conscripts off the streets.