If you're asking whether you need a lawyer to draft a contract, legally, the answer is no. Anyone can draft a contract on their own and as long as the elements above are included and both parties are legally competent and consent to the agreement, it is generally lawful.
How to write a contract agreement in 7 steps. Determine the type of contract required. Confirm the necessary parties. Choose someone to draft the contract. Write the contract with the proper formatting. Review the written contract with a lawyer. Send the contract agreement for review or revisions.
The biggest difference is that an SPA is the sale of all shares, and an APA is the sale of selected assets. Therefore, they are both different transactions and have different procedures.