Are the two op-amp terminals at equal bias for positive feedback?
No: even though the op amp input terminal \$V_{IN-}\$ is driven to nearly the same voltage as \$V_{IN+}\$ when configured for negative feedback, when configured for positive feedback \$V_{IN+}\$ is not driven to the same voltage as \$V_{IN-}\$, and in fact it's driven away from the \$V_{IN-}\$ voltage.
Negative Feedback Configuration is Convergent
In negative feedback configuration, \$V_{IN+}\$ is the reference, and the feedback network drives \$V_{IN-}\$ such that \$V_{IN-} = V_{IN+} - (V_{OUT} / A_{v})\$, where \$A_{v}\$ is open-loop gain. If the output \$V_{OUT}\$ is &quot;too big&quot; compared to the target reference value, then the feedback \$V_{IN-}\$ is also &quot;too big&quot;, and since \$V_{IN-}\$ &gt; \$V_{IN+}\$ then \$V_{OUT}\$ is driven to a lower voltage, until \$V_{IN-}\$ reaches nearly the same voltage as \$V_{IN+}\$. Also, \$V_{OUT}\$ will be driven to whatever value the feedback network requires it to be to make \$V_{IN-}\$ match the reference \$V_{IN+}\$.
Positive Feedback Configuration is Divergent
In positive feedback configuration, \$V_{IN-}\$ is the reference, and the feedback network drives \$V_{IN+}\$ such that \$V_{IN+} = (V_{OUT} / A_{v}) + V_{IN-}\$, where \$A_{v}\$ is open-loop gain. If the output \$V_{OUT}\$ is &quot;too big&quot; compared to the target reference value, then the feedback \$V_{IN+}\$ is also &quot;too big&quot;, and since \$V_{IN+}\$ &gt; \$V_{IN-}\$ then \$V_{OUT}\$ is driven to an even higher voltage, until \$V_{OUT}\$ reaches the practical limit of how close the output can get to the power supply voltage.
Positive feedback can be useful when designing a memory cell, or when using hysteresis to help a comparator avoid responding to certain types of noise sources. But for DC amplifiers this effect is unwanted.