The study of viscoelastic and second grade fluids has become a cornerstone of modern continuum mechanics due to its immense relevance in polymer processing, biological transport, microfluidics, and magnetohydrodynamic technologies. Unlike Newtonian fluids, viscoelastic fluids exhibit time dependent memory and elastic recoil, enabling them to store and release mechanical energy in ways that fundamentally alter flow patterns, boundary layer behavior, and particle transport. This work presents a comprehensive theoretical and analytical synthesis of second grade and fractional second grade fluid dynamics in the context of stretching surfaces, microfluidic channels, porous media, and magnetohydrodynamic environments. By integrating classical second grade models with fractional calculus based memory representations, this study constructs a unified continuum description capable of representing both short term elasticity and long term hereditary behavior. The analysis is grounded exclusively in authoritative research spanning microfluidic filament dynamics, propulsion in viscoelastic media, particle migration, MHD effects, and fractional derivative modeling. Emphasis is placed on how viscoelastic stresses modify momentum diffusion, interfacial stability, boundary layer formation, and energy transport across a wide range of physical configurations. The theoretical framework is expanded to cover unsteady shear flows, porous substrates, thermal gradients, slip boundary effects, and nonuniform magnetic fields, enabling a multidimensional perspective on non Newtonian transport. A detailed interpretation is provided for how second grade and fractional order effects generate flow instabilities, modify wave propagation, alter drag and propulsion mechanisms, and influence heat and mass transfer in stretching sheet and channel systems. The results demonstrate that the coupling between elastic stress relaxation, fractional memory, and magnetic damping leads to flow regimes that cannot be captured by conventional Newtonian or integer order models. These regimes include delayed boundary layer development, enhanced particle migration, non monotonic velocity profiles, and memory induced damping or amplification of disturbances. The work further establishes that fractional order parameters act as physically meaningful measures of fluid memory, enabling precise tuning of transport behavior in microfluidic and industrial applications. The article concludes by identifying how these models provide a theoretical foundation for next generation polymer processing, biofluid transport, and MHD based microdevices, while also addressing their limitations and future extensions.