Well, it all depends on taste. With condos, you have someone typically above and below and either side of you. However, condos do sometimes provide more amenities than townhomes, especially in the city, like fitness rooms, club rooms, etc. And often in the city, condos are closer to the hot spots. However, condos rarely ever have yards.
Townhomes often have some grass and are on the street level - no elevator. This often lowers their monthly assessments. They are sometimes larger and only usually share two walls with others, at maximum.
One other consideration is financing. If you have a downpayment less than 5 or 10%, you will need FHA approval on a condominium. Townhomes can be condo ownership, but also can be Fee Simple, which can be easier to finance.
Insurance requirements are difference based on condo or fee simple ownership too. Condo ownership includes insurance in the assessment. You only have to pay for contents insurance to protect your belongings.
Again - a few differences, but mostly a matter of taste. Good luck!