It is expected for the Composer Flow report and the Composer Conversion report data not to match, since the data within the reports is different. Exposures and executions are different: exposures are logged when a template is loaded, no matter whether the user saw the template or not, whereas executions will represent the number of times the experience itself was executed.
An Execution happens when the user meets the criteria of the experience settings (User segmentation and Effective pages). An execution may be registered even if a user doesn't reach an Action card. An execution is registered after every pageview generated by a user. Repeat visits from the same user count as new executions.
An Exposure is the number of times an offer is shown to the user. It is logged when the Offer template is loaded, no matter if the user saw it or didn't. Based on this, if the page is refreshed, it will be counted as a new exposure.