I agree with Shane, Reckon Accounts has more functions and options to Reckon One. Hence, Reckon One is a more simplified platform compared to that of say Reckon Hosted. It really comes down to what you want to achieve and how much you are prepared to pay.
"Prettier Invoices" is a Windows program that lets you create much prettier invoices than Reckon One lets you by giving you more control over the look of your invoices. You can add extra text, images, or add a watermark image to your invoices.
For more details: https://www.reckon.com/marketplace/add-on/prettier-invoices/
A free trial is available for you to test it out.