For a normalized univalent function \( f(z)= z + \sum _{n=2}^{\infty } a_n z^n \) defined in the unit disc \( \mathbb {D} \) , the logarithmic coefficients \( \gamma _n \) are defined by \( \log (f(z)/z) = 2 \sum _{n=1}^{\infty } \gamma _n z^n \) . In this paper, we obtain upper bounds for \( |\gamma _3| - |\gamma _2| \) for functions satisfying \( z f'(z)/f(z) + \lambda z^2 f''(z)/f(z) \prec \varphi (z) \) , \(\lambda \ge 0\) . Further, we derive upper bounds for \( |\gamma _3| - |\gamma _2| \) for Ma–Minda starlike functions satisfying the subordination \( z f'(z)/f(z) \prec \varphi (z) \) , as well as for the corresponding class of Ma–Minda convex functions for various choices of \( \varphi \) . We also obtain upper bounds for \( |\gamma _2| - |\gamma _1| \) and \( |\gamma _3| - |\gamma _2| \) for functions satisfying \( 1 + (1/b)(f'(z) - 1) \prec \varphi (z) \) , as well as for related classes of analytic functions.
