Gravimetric analysis determines a substance's quantity by converting it into a pure, weighable solid and measuring that solid's mass directly, while volumetric analysis, titration especially, determines a substance's quantity by measuring exactly how much of a second, precisely known solution is needed to react completely with it. Both methods can reach genuinely high precision using nothing more sophisticated than a balance and carefully measured liquid volumes, no electronics or specialised instrumentation required at all.
Gravimetric analysis converts a dissolved substance into a solid that can simply be weighed
Gravimetric analysis converts the substance being measured into an insoluble, pure solid precipitate through a specific chemical reaction, then filters that precipitate out and dries it completely before weighing it directly. The original substance's quantity is then calculated back from the weighed solid's mass, using the known, fixed chemical relationship between the original substance and the precipitate it was converted into.
Titration instead tracks exactly how much of a known solution a reaction actually needs
In volumetric analysis, a solution of precisely known concentration is added gradually to the sample until the reaction between the two is exactly complete, signalled by a colour change or another clearly observable endpoint indicator. The volume of that known solution actually used by the time the reaction finishes lets a chemist calculate the original sample's own concentration directly, using the known stoichiometry of the reaction between the two.
What we're still unsure about
That gravimetric and volumetric analysis can both reach high precision using simple, well-established tools and methods is well established, uncontroversial analytical chemistry. What's genuinely worth flagging is that each method depends on a step that's easy to get subtly wrong, gravimetric analysis needs its precipitate to be completely pure and completely dry before weighing, any trapped moisture or co-precipitated impurity throws the final result off, and volumetric analysis depends on correctly judging the reaction's endpoint, overshooting or undershooting it even slightly introduces a real, and not always immediately obvious, error into the calculated result.
This sits inside Gravimetric & Volumetric Analysis, one of seven topics in Analytical Chemistry, one of six domains in Chemistry, one of seventeen subjects the app can quiz you on.