The difference between the options is reflected in the price, with basic exercise bikes starting from as low as  $150/ £100, while the entry level to a smart bike is upwards of £1,895/  £1500 and travelling well in excess of $2,500/ £3,000, often requiring a monthly subscription to get the most benefit.
Indoor bikes which blend both exercise bikes and smart bikes together, 1n the form of an interactive wi-fi enabled spin bike, can be a good compromise, enabling you to join on line classes for more motivational cardio session at home. Although it's worth noting that although the initial outlay might be a lot less than a smart bike, a monthly subscription service can make it more expensive in the long run.
Which is the right one for you depends which functions and features are important to you.
An entry-level model will allow you to get a spin on and get fit. Spend more, and you'll enjoy ANT+ and Bluetooth connectivity, so you can train using indoor training apps such as Zwift or The Sufferfest.