Am learning about implementing DB transactions in golang and for that, the instructor was creating a query object which will be having access to all the CRUD methods. But he also have a object which is having the Query as a data member in the struct. Why cant we use that?

type Store struct {
    *Queries
    db *sql.DB // Required for creating transactions
}

// Method to generate a store object
func NewStore(db *sql.DB) *Store {
    return &Store{
        db:      db,
        Queries: New(db),
    }
}

// executeTx execute the function given to it
func (store *Store) executeTx(ctx context.Context, fn func(*Queries) error) error {
    // Initiate the transaction
    tx, err := store.db.BeginTx(ctx, nil)
    if err != nil {
        return err
    }
    // The New() is decalred for DBTX inteface and both sql.DB and sql.Tx satisfy them
    // This will return a query object which can be used for the execution of the function.
    // We can also use the query object of the store too but thats just for composition
    q := New(tx)
    err = fn(q)
    if err != nil {
        rbError := tx.Rollback()
        if rbError != nil {
            return fmt.Errorf("tx err: %v, rollback err: %v", err, rbError)
        }
        return err
    }
    return tx.Commit()
}

Here, the Queries is already a struct which is declared as:

type DBTX interface {
    ExecContext(context.Context, string, ...interface{}) (sql.Result, error)
    PrepareContext(context.Context, string) (*sql.Stmt, error)
    QueryContext(context.Context, string, ...interface{}) (*sql.Rows, error)
    QueryRowContext(context.Context, string, ...interface{}) *sql.Row
}

func New(db DBTX) *Queries {
    return &Queries{db: db}
}

type Queries struct {
    db DBTX
}

func (q *Queries) WithTx(tx *sql.Tx) *Queries {
    return &Queries{
        db: tx,
    }
}

So my question is,

q := New(tx) err = fn(q)
being used but can we use it like this too?
err = fn(store.Queries)

I tried executing the code with the Query from the store struct and it works but will there be any difference between the two.