Step 1: Analyze Statement I.
For a conservative force field, the work done in moving a particle from position \( \vec{r}_1 \) to \( \vec{r}_2 \) is equal to the negative change in potential energy.
Mathematically,
\[
W = -\int_{\vec{r}_1}^{\vec{r}_2} \vec{F} \cdot d\vec{r}.
\]
This expression correctly represents the work done by a conservative force.
Hence, Statement I is true.
Step 2: Analyze Statement II.
Although a particle can move between two points along infinitely many paths, the defining property of a conservative force is that the work done depends only on the initial and final positions and not on the path followed.
Therefore, the work done by a conservative force does not change with the path.
Hence, Statement II is false.
Step 3: Final conclusion.
Statement I is true but Statement II is false.
Final Answer:
\[
\boxed{\text{Statement I is true but Statement II is false}}
\]