In this work, we demonstrate that the structure of solution aggregates across length scales can be largely modulated by solvent selectivity towards polymer backbone/side chain as well as solution temperature. We discover several distinct structures of solution aggregates through a combination of small angle X-ray scattering (SAXS), electron diffraction, optical and electron microscopy, and ultraviolet-visible (UV-vis) absorption spectroscopy. Surprisingly, tuning the solution aggregate structures grants access to three drastically different assembly pathways that define the film morphology and charge carrier mobility. Through this example, we demonstrate the power of controlling assembly pathways and properties of conjugated polymers through tuning the precise aggregate structures. Our findings further raise the point that "not all aggregates are made the same": it is important to differentiate different states of aggregation when discussing the impact of solution aggregation on (opto)electronic properties and beyond.