$\def\pa{\mathsf{PA}}\def\zff{\mathsf{ZF_{fin}}}\def\zffm{\mathsf{ZF_{fin}^-}}$Your theory (let me denote it $T$ for the moment) is mutually interpretable with $\pa$, but it is not bi-interpretable with $\pa$, and a fortiori not synonymous. On the one hand, it is easy to see that $\pa$ interprets $T$ using Ackermann’s interpretation ($n\in x$ iff the $n$th bit in the binary expansion of $x$ is $1$), as mentioned in Joel’s answer. For an interpretation of $\pa$ in $T$, it is easiest to make a short detour through classical results on finite set theory by Mostowski (and if something I mention is not due to Mostowski, it is in the works of Sochor). $\pa$ is bi-interpretable with the theory $\zff$ of finite sets, which can be axiomatized by 1. Extensionality 2. Existence of $\varnothing$ 3. Existence of $x\cup\{y\}$ for all $x$ and $y$ 4. Induction: $\phi(\varnothing)\land\forall x,y\,\bigl(\phi(x)\to\phi(x\cup\{y\})\bigr)\to\forall x\,\phi(x)$ 5. $\in$-induction: $\forall x\,\bigl(\forall y\in x\,\phi(y)\to\phi(x)\bigr)\to\forall x\,\phi(x)$ Moreover, the theory $\zffm$ axiomatized by 1–4 interprets $\zff$ (hence $\pa$), namely it proves axioms of $\zff$ relativized to the class WF of hereditarily well-founded sets: $x$ is in WF iff there is a transitive set $y\supseteq x$ such that every nonempty subset of $y$ has an $\in$-minimal element. (It is a longish but straightforward exercise to show that $\zffm$ proves all the usual axioms of ZFC except infinity and foundation; some of these may be useful for verification of this interpretation.) Now, I claim that $T$ proves $\zffm$. Axioms 1–3 are straightforward. For 4, first note that $T$ proves that every nonminimal element has a predecessor (as the set of strictly smaller elements has a maximal element), and (using Sets and Well-founedness) order induction $\forall x\,\bigl(\forall y<x\,\phi(y)\to\phi(x)\bigr)\to\forall x\,\phi(x)$, which together imply usual induction $$\phi(0)\land\forall x,y\,\bigl(\phi(x)\land S(x,y)\to\phi(y)\bigr)\to\forall x\,\phi(x),$$ where $0$ is the smallest element, and $S(x,y)$ iff $y$ is the successor of $x$. Then assuming $$\phi(\varnothing)\land\forall x,y\,\bigl(\phi(x)\to\phi(x\cup\{y\})\bigr),$$ we can prove $$\forall x\,(\forall y\in x\,y\le n\to\phi(x))$$ by induction on $n$, which implies $\forall x\,\phi(x)$ using Finiteness. $\def\N{\mathbb N}$Finally, to show that $\pa$ is not bi-interpretable with $T$, the key observation is that $T$ has lots of nonisomorphic (and not elementarily equivalent) standard models. Here, I call a model $(M,<,\in)\models T$ standard if $(M,<)$ is well founded (necessarily of order-type $\omega$). For every permutation $\sigma\colon\N\to\N$, we have $\N_\sigma=(\N,<,\in_\sigma)\models T$, where $$n\in_\sigma x\iff\text{the $n$th bit of $\sigma(x)$ is $1$.}$$ Now, assume for contradiction that $F$ is an interpretation of $\pa$ in $T$ and $G$ is an interpretation of $T$ in $\pa$ such that $F\circ G$ is definably isomorphic to the identity self-interpretation of $T$. Fix permutations $\sigma\ne\tau$. Then $F$ induces models $\N_\sigma^F$ and $\N_\tau^F$ of $\pa$, and $G$ induces a copy of $\N_\sigma$ definable in $\N_\sigma^F$ and a copy of $\N_\tau$ definable in $\N^F_\tau$, using the *same* definitions. Since $\N_\sigma^F$ has full induction schema, it can define an embedding $f$ of the universe into the internal copy of $\N_\sigma$ such that $f(0)$ is the least element of $\N_\sigma$, and $f(n+1)$ is the successor (as computed in $\N_\sigma$) of $f(n)$. Since $f$ is an order embedding into a well-ordered set, its domain must be well ordered as well: that is, $\N_\sigma^F$ must be isomorphic to the standard model $\N$ of $\pa$. The same argument applies to $\N_\tau^F$, thus in particular, $\N_\sigma^F\simeq\N_\tau^F$. But then their internal models of $T$, viz. $\N_\sigma$ and $\N_\tau$, must be isomorphic as well, as they are defined by the same formulas. This is a contradiction, as $\N_\sigma$ and $\N_\tau$ are not even elementarily equivalent (they disagree on some sentences of the form $\overline n\in\overline m$, where $\overline n$ denotes the $n$th least element according to $<$). Note that we have used only one half of the definition of bi-interpretability, thus the argument above actually shows that $T$ is not an interpretation retract of $\pa$.