I'd say that while they are similar and can sometimes be used for the same task they serve different purposes.
The Directory + Dynamic Input tool combo is more likely to be a Directory + Filter + Dynamic Input combination or a Directory + Sort + Sample + Dynamic Input combo. A common use case is where a folder has many data files with the same schema and you want to read in just the most recent data file. You can sort by Date Modified and then Sample to get the first record to get the most recent file which you then read with the Dynamic Input. If you wanted all files created after a certain date you could use the Filter Tool to handle that.
The Input Data tool with wildcards is just for reading in many files with the same schema. It's simpler and it has the advantage of working with more file types - I don't believe you can read in xlsx files for example with the Directory + Dynamic Input tool combo (without having to add a formula tool - thanks Rod!)