SOAP UI 5.0-groovy Automation

You can use the xml parser to do the same.

//eg response 1:

File OrginalFile = new File(FilenameAsInputXmlFile);
def String FetchXmlData = OrginalFile.getText();
def response = new XmlSlurper().parseText(FetchXmlData)

def firstreqvalue=response.YourTagname[0]

//eg response 2:

File OrginalFile2 = new File(FilenameAsInputXmlFile);
def String FetchXmlData2 = OrginalFile.getText();
def response2 = new XmlSlurper().parseText(FetchXmlData)

def firstreqvalue2=response2.YourTagname[0]

if(response2 ==response){

//your code

}

As you have Mentioned You have 2 WSDL. So you have to create 2 test suite, each is related to corresponding operations, I am assuming Old service vs new Services.

In your First test suite ( Old ), you can add test cases which can have a groovy test step. that step will save Responses to the local system.

eg..

        def outPutFileLocationRes01="C://TestSection//Res01.xml";
	def response = context.expand( '${testCaseNameOfYourService#Response}' )
	def f = new File(outPutFileLocationRes01)
	f.write(response, "UTF-8")
	log.info "Responses is save in local :"+outPutFileLocationRes01

In your Second test suite ( New ), you can add test cases which can have a groovy test step. that step will save Responses to the local system.

eg..

        def outPutFileLocationRes02="C://TestSection//Res02.xml";
	def response = context.expand( '${testCaseNameOfYourService#Response}' )
	def f = new File(outPutFileLocationRes02)
	f.write(response, "UTF-8")
	log.info "Responses is save in local :"+outPutFileLocationRes02

Once Both Operations is Compleated Either you can create a new project to use the existing project to make new testSuite , That suite should have testcase along with  testStep groovy Script

Where you can write the read the both responses (new and old) from local system and parse to as xml, read entire XML and do the validations.

eg.. (below example is just considering one tag) Please share your responses next time for more insight.

        FilenameAsInputXmlFileRes01="C://TestSection//Res01.xml"
	File OrginalFile01 = new File(FilenameAsInputXmlFileRes01);
	def String FetchXmlData01 = OrginalFile01.getText();
	def response01 = new XmlSlurper().parseText(FetchXmlData01)
	String personId=response01.personId;
	
	
	FilenameAsInputXmlFileRes02="C://TestSection//Res02.xml"
	File OrginalFile02 = new File(FilenameAsInputXmlFileRes02);
	def String FetchXmlData02 = OrginalFile02.getText();
	def response02 = new XmlSlurper().parseText(FetchXmlData02)
	String personIdentification=response02.personIdentification;
	
	
	if(personId.trim()==personIdentification.trim())
	{
			log.info "Both Tags Values are same -> personId : [ "+ personId + " ] [ personIdentification : [  " + personIdentification + " ]"
			//return true;
	}else{
			log.info "Both Tags Values are Not same -> personId : [ "+ personId + " ] [ personIdentification : [  " + personIdentification + " ]"
			//return false;
	}