The difference is whether you have a home office or not. Working from home is not the same as having a home office. A home office is your place of business. If you have a home office, travel from the office to the client is deductible. If you don't, it isn't.
Pub 463
Office in the home.
If you have an office in your home that qualifies as a principal place of business, you can deduct your daily transportation costs between your home and another work location in the same trade or business. (See Pub. 587, Business Use of Your Home, for information on determining if your home office qualifies as a principal place of business.)
