The theoretical work can develop ideas, explain phenomena. This can only be beneficial if it is realized through experience. The theory must be validated by experience. poor countries must focus their efforts on the engineering sciences.
TRW and ERW - Both are incomplete without each other
Theoretical RW = Planning and ideas generation
Experimental RW = Acting on the plans (in vitro or in vivo)
TRW is like review of literature
and ERW is like materials and methods
or we can say, A PhD scholar in History is a Theoretical researcher, but a PhD scholar in microbiology is both Theoretical and Experimental researcher.
Theoretical Research is a non-empirical approach to research. It has its findings based on existing theories and hypothesis. The conclusions are drawn from observations and logical reasons based on proven theory.
Practical research has its findings based on the verification through experiments and observations. It consists of the empirical study of the topic under research and chiefly consists of hands on approach. The Muslim scholar Ibn al-Haytham a.k.a as Al-Hazen has been attributed as the inventor of the scientific method, due to his emphasis on experimental data and reproducibility of its results. Controlled experiments, the cornerstone of practical research, can be seen in the works of Jabir Ibn Hayyan (721-815 CE), Al-Battani (853-929) and Al-Hazen (965-1039).