Final answer:
Major differences that need to be worked out between the United States and the European Union include aspects related to agriculture, genetically modified crops, tariff reduction, and cross-border investment.
Step-by-step explanation:
The major differences that need to be worked out before an agreement can be reached between the United States and the European Union include aspects related to agriculture, genetically modified crops, tariff reduction, and cross-border investment. Job creation is not one of the differences that need to be worked out.